单项选择题

In a diesel engine, when installing new piston rings it is important to check()
Ⅰ.ring gap clearance
Ⅱ.side clearance

A.Ⅰ only
B.Ⅱ only
C.both Ⅰ and Ⅱ
D.neither Ⅰnor Ⅱ