In The Importance of Being Earnest, why does Gwendolen always travel with her diary?

In The Importance of Being Earnest, why does Gwendolen always travel with her diary?
1 point

a. She wants to give it to Jack as a birthday present.
b. She believes people should always have something sensational to read on the train.
c. She is hoping to write a three-volume novel based on her life.
d. She wants to be ready if she has to prove an event took place.