The correct answer from question 13 proves A can be true. R tests G on the second day.
The following diagram proves B, D and E could be true:

C is CORRECT. If T tests F on the second day, then T must test H on the first day. YS have to test G, there’s no space anywhere else.

This doesn’t work: there’s no place to put R for the first day of testing. R can’t test F, so R would have to test J on both the first and second days. That doesn’t work.

How could this be solved most time effectively? Is plugging in variables to check answers the best way?