Enquiries on 2018 September

Which of the following statements defines moral hazard in relation to insurance?
A Moral hazard describes the fact that people who know that they are a
particularly bad risk are more inclined to take out insurance.
B Moral hazard describes the fact that a policyholder may act in a way which
makes the insured event more likely to occur.
C Moral hazard describes the fact that people who know that they are a
particularly bad risk are less inclined to take out insurance.
D Moral hazard describes the risk that an insurance company will face false
insurance claims.
May I know where can i get the true definition ? May I know if you could elaborate on this ?