While Studying for This Quiz You Realize That You Still $\degree$

Multiple Choice

While studying for this quiz you realize that you still have 100 g of lukewarm coffee at 40 $\degree$ C left in a paper cup. When you pour 20 g of boiling water into the cup, the temperature of the resulting coffee-like mixture will be now

A) 50 $\degree$ C.
B) 60 $\degree$ C.
C) 67 $\degree$ C.
D) 70 $\degree$ C.
E) 80 $\degree$ C.