The sentence refers to a past continuous action that was happening when another action ("heard") occurred.
The correct structure for past continuous is:
was/were + present participle (verb + -ing).
The correct form is:
"was lying" (past continuous).
The correct sentence should be:
"He was lying on the bed when he heard a noise."
Thus, the correct answer is Option A ("was lying").
Arun’s present age in years is 40% of Barun’s. In another few years, Arun’s age will be half of Barun’s. By what percentage will Barun’s age increase during this period?