It was kind of a trick question (which I?ll get to later) since nothing ever happens in a vacuum, but the best answers were C and D.

In June of 1966, the AF Chief of Staff directed a study to determine if the AF was providing satisfactory support to the Army in Vietnam. By August the results were reported that the Army was generally satisfied with AF support but that they were excluding the AF from certain missions, and increasing the expenditures for more armament of the AH-1 and working towards something called the Advanced Aerial Fire Support System (You will more likely know it as the AH-56A Cheyenne). Another finding was that the multi-role approach (i.e. using aircraft such as A-7D for CAS when needed) wouldn?t satisfy the perceived need for ?helicopter escort? and ?fire support? roles.  As a result of this study, the AF immediately launched an effort to field a dedicated CAS aircraft that would replace the (believed to be) best CAS aircraft at the time: the A-1 Skyraider. An important planned improvement over the Skyraider would be a better capability against hard targets. The program went through two major rounds of capability and mission analyses and numerous minor tweaks before the final A-X requirements were issued.

Background (the trick part):

Existing Doctrine in 1965 allowed the Army to pursue rotary wing solutions to providing ?suppressive fire? support that could augment but not replace CAS. The Army was then developing its Air Mobile doctrine and sought to expand acquisition and use of both rotary and fixed wing aircraft to support it. In particular, the Army?s effort to acquire more Caribou and Mohawk aircraft was seen as trespassing into AF missions and the effort was shot down at the SecDef and NOT AF level (yes, McNamara) .  This ?fixed wing expansion? attempt, combined with the Army?s efforts to field the Cheyenne (the roots of which reach back to before major involvement in Vietnam, circa ?62), which was seen by some in the AF as evidence of the Army?s intent to expand beyond the ?suppressive fire? and into the CAS mission due to the quantum leap ahead in capabilities (high speed, advanced avionics, 30mm gun, grenade launcher/minigun, etc) compared to its precursors increased tensions between the AF and Army.  There were Congresscritters taking sides (largely Army) in the debate, and one in particular, Rep Otis Pike, played a major role in bringing things to a head. He convened a hearing in late ?65 and the Committee findings released in Spring of ?66 criticized the AF for not being more serious about fielding a better CAS capability. This was in spite of the already in-work effort to field an interim platform (A-7D). IMHO, Pike?s background as a WWII Marine aviator probably poisoned the well on the issue, since Marine Aviation?s sole reason for existence is to support the Rifleman on the ground. Like many of my ground-dwelling brethren, Pike probably confused/confuses CAS with Airpower, instead of recognizing the first as a subset of the second. As mentioned earlier, the AF found the Army generally happy with the AF?s CAS with the exceptions related to helo operations, so it appears that ?someone? was overstating the case against AF CAS for reasons that are anyone?s guess.

A cynic would assume that the 'Army' or nefarious members thereof was consciously attempting a turf takeover to support their Airmobile aspirations, but a more like (to me) explanation is that it was more along the lines of the Army wanting to control as much of their own destiny as possible by making as many of their fires as organic as possible when in contact with the enemy, without concern for the unintended consequences on eliminating the enemy, or reducing his capabilities PRIOR to contact.  I believe Desert Storm and Iraqi Freedom operations have since validated the second explanation.