In People with Normal Circadian Clocks,what Effect Does Melatonin Taken

In people with normal circadian clocks,what effect does melatonin taken in pill form have on jet lag?

A) It helps people to adjust to jet lag.
B) It helps people to adjust to jet lag, but only if traveling east to west.
C) It helps people to adjust to jet lag, but only if traveling west to east.
D) It was no more effective than a placebo in reducing jet lag.