Suppose an unexpected announcement of a large dividend on a stock doesn't affect its share price, which of the following is false?

a. If the ex-dividend day is before the maturity of a call option on the stock, the announcement should have a negative effect on the option value.

b. If the ex-dividend day is after the maturity of a call option on the stock, the announcement should have a negative effect on the option value.

c. If the ex-dividend day is after the maturity of a put option on the stock, the announcement should have no effect on the option value.

d. If the ex-dividend day is before the maturity of a put option on the stock, the announcement should have a positive effect on the option value.

Please also explain why.