Data Sufficiency

If car X followed car Y across a certain bridge that is 1/2 mile long, how many seconds did it take car X to travel across the bridge?
(1) Car X drove onto the bridge edactly 3 secounds after car Y drove off the bridge
(2) Car Y travelled across the bridge at a constant speed of 30 miles per hour.

By the way..the answer is C, but kind of confused..

I will go with E.
Anyone going for C