The most accurate explanation for why a shoe and a shirt take different amounts of time to fall to the ground is:
The masses of the two objects are the same, but they are affected differently by air resistance.
This answer highlights that while both objects are affected by gravity equally, their shapes and surfaces cause them to experience different amounts of air resistance as they fall, impacting their falling times. However, if the shoe is significantly heavier or has a different shape than the shirt, then the other options could become relevant. But generally, for lighter objects like a shoe and a shirt, air resistance plays a more significant role.