H and K can only go together on Friday. If they were together on Wednesday, then J would be on Thursday, and G would be on Friday. This is too many clients between K and G.
If they were together on Thursday, we can’t have out JG block.
Okay, so H and K are on Friday, and H is in the morning due to Rule 1. Then, to make sure there’s at most one client before G and K, G will have to go on Thursday afternoon.
We know J has to go on the day before G. Now we can have two configurations. In the first one, J goes on Wednesday morning, so L has to go on Thursday morning.
In the second configuration, J goes on Wednesday afternoon, and L can go on either Wednesday or Thursday morning.
Thus, C is CORRECT. J can go on either Wednesday morning or afternoon.
A is incorrect. G can’t be on Friday since H and K fill all the slots.
B is incorrect since H must go on Friday.
D is incorrect. K must be on Friday.
E is incorrect. L can’t be scheduled on Friday since H and K are there.