Subject: mathqa
Question: monica planned her birthday party . she prepared 5 muffins for each of her guests and kept aside two additional muffins in case someone will want extra . after the party , it turned out that one of the guests did n ' t come but every one of the guests that did come ate 6 muffins and 6 muffins remained . how many guests did monica plan on ?
Option: 
A: 5 .
B: 4 .
C: 2 .
D: 6 .
Answer: C