Question $13$: Which of the following would decrease the value of an American call option?

I. The exercise price is decreased.

II$.$ The value of the underlying asset increases.

III. The variance of the underlying asset's returns increases

a$)$ I only

b$)$ I, II and III

c$)$ II and III only

d$)$ I and II only

e$)$ None of $a,b,c$ or $d$ is correct