In The Importance of Being Earnest, what leads Algernon to suspect

In The Importance of Being Earnest, what leads Algernon to suspect that Ernest/Jack is a Bunburyist? 1 point

a. He sees an inscription on a cigarette case.
b. Gwendolen tells him that his name is really Jack.
c. Algernon finds a handkerchief embroidered “Jack Worthing” in his friend’s jacket pocket.
d. He overhears him call himself Jack to a friend.