DELVEDelve means to explore about something, to look into a situation.
Right Answer is: A
Delve means to explore about something, to look into a situation.
Inquire means the same as delve, to investigate a situation.
Insolvency is the condition of being unable to pay debts or of having greater liabilities than assets.
Incredulity is the state or quality of being incredulous; disbelief.
Impromptu means with little or no preparation; extemporaneously.
Hence the answer is option A.