DRAG DROP
You are developing a Windows Store app.
You need to identify the appropriate REST verbs for the app.
Which verbs should you use? (To answer, drag the appropriate verbs to the correct locations
in the answer area. Each verb may be used once, more than once, or not at all. You may
need to drag the split bar between panes or scroll to view content.)
Answer: 
Merge?¿
Update changed data = PATCH, if there is no a PATCH option, the answer should be PUT.
https://msdn.microsoft.com/en-us/library/dd541276.aspx
I dont understand because the question use MERGE instead of PATCH.
MERGE would be a right option but, you usually (me always) use PATCH method.