Read the following excerpt from "shooting an elephant" by george orwell:

early one morning the sub-inspector at a police station the other end of the town rang me up on the phone and said that an elephant was ravaging the bazaar. would i come and do something about it? i did not know what i could do, but i wanted to see what was happening and i got on to a pony and started out. i took my rifle, an old 44 winchester and much too small to kill an elephant, but i thought the noise might be useful in terrorem.
based on this excerpt, what does "in terrorem" most likely mean?
a. calming fear
b. resembling fear
c. remembering fear
d. causing fear