The correct option is A During National Emergency
While a National Emergency is in action, the Parliament may by law extend the normal term of the Lok Sabha for a period of a single year at a time, and it can renew it any number of times as thinks fit. But it cannot extend to beyond a period of 6 months after the Emergency has ceased to operate. Hence, Option A is correct. The rest of the conditions cannot extend the term of Lok Sabha, hence, incorrect.