Which of these fixed wing aircraft is equipped with 30mm, 105mm, and small diameter bombs?

The AC-130J is the correct answer because this aircraft is specifically designed for close air support and ground attack missions. It is equipped with a variety of ordnance that includes a 30mm cannon, a 105mm howitzer, and the capability to deploy small diameter bombs. The combination of these weapons makes the AC-130J highly versatile for engaging a range of targets in support of ground troops.

In contrast, while the F-16 and the F/A-18 are multi-role fighters capable of delivering various munitions, they do not specifically feature the 105mm cannon or are primarily characterized by their other armaments. The B-1B, while capable of carrying a wide array of bombs and munitions, is distinct from the AC-130J in its operational role and weaponry configuration, primarily focusing on bomb dropping rather than the close air support missions that the AC-130J specializes in.