Answer from cs61c-am (Michael Moeng 16464697) for Question 4
I do not totally understand wheter the upper-left block is the root of the program or whether the whole system is a linked list, but i will assume that it is a root.

reference count will not reclaim anything because each node(except the root) has a pointer pointing to it.

mark and sweep will not reclaim anything because traversing the program from the root will hit every block, so nothing will be deleted.