Which of the following statements is false regarding the effect of time on options prices?

a. an increase in days to expiration while keeping all other variables constant has the effect of increasing the value of call options

b. an increase in days to expiration while keeping all other variables constant has the effect of increasing the value of put options

c. an increase in days to expiration while keeping all other variables constant has no effect on the value of call and put options because it has nothing to do with the expected volatility of the underlying price

d. none of the above