Final answer:
The APFU replaced the PT Uniform (Physical Training Uniform) in 2017, not the ACU, BDU, or ASU, as it is specifically designed for physical training within the Army.
Step-by-step explanation:
The APFU (Army Physical Fitness Uniform) replaced the PT Uniform (Physical Training Uniform) in 2017. The APFU was introduced to offer a more comfortable and versatile uniform for soldiers to wear during physical training. It is important to note that it did not replace the ACU (Army Combat Uniform), the BDU (Battle Dress Uniform), or the ASU (Army Service Uniform) as each has its specific purpose within the Army's dress regulations. The PT uniform that the APFU replaced was designed for fitness exercises and activities, not for combat or ceremonial purposes.