This is not Cat B! This is the 113th division of 38th army. Look at the batch, it's this one:
The words at the bottom is the Chinese pronunciation of "flying tiger division". In Korean War, this division once marched 70 km in one night and had combat several times during the march, then successfully cut the rear of a group of US army. There was a movie called "flying tiger" for this event. That's why they use it as the nickname of the division.
I think these are old pictures, and not taken by normal soldiers, but by some professional photographers. It's very rare for Chinese soldiers to have cameras. I also don't think normal solders are allowed to take cameras in a drill.