As a Youngster, You Drive a Nail in the Trunk

As a youngster, you drive a nail in the trunk of a young tree that is 3 metres tall. The nail is about 1.5 metres from the ground. Fifteen years later, you return and discover that the tree has grown to a height of 30 metres. About how many metres above the ground is the nail?

A) 0.5
B) 1.5
C) 3.0
D) 15.0
E) 28.5