Answer from cs61c-ac (U alias Vitoria Lok 16597715) for Question 2
a is false
b is true
c is true
d is false

If the block being freed is adjacent to a free block on either side, it is coalesced with it into a single bigger block, so the number of free blocks is the same or decrease by 1. (eg. 2 original blocks plus 1 new block placed in the middle of them, results in 1 block at the end).