In a four stroke cycle petrol engine, the inlet valve

A)
opens at top dead centre and closes at bottom dead centre
B)
opens at 20° before top dead centre and closes at 40° after bottom dead centre
C)
opens at 20° after top dead centre and closes at 20° before bottom dead centre id) may open or close anywhere
D)
None of the above

Correct Answer : Option (B) :   opens at 20° before top dead centre and closes at 40° after bottom dead centre