Answer from cs61c-ep (Hao Wen Vivian Chong 15826235) for Question 4
Reference count method: Yes. Since the top left node does not have any pointers going to it (not being pointed to by a root (?)) it will be deleted. In turn, all of the other nodes will be deleted since the three pointers coming from that node will be gone, and there will be no way to reach the other nodes.

Mark and sweep method: Yes. Since the objects cannot be reached from a root, they will not be marked, and when the sweep happens, they will all be reclaimed.