Sam is walking in a straight line towards a lamp post which is 8\:m high. When he is 12\:m away from the lamp post, his shadow is 4\:m in length. When he is 8\:m from the lamp post, what is the length of his shadow?
Answer Choices
A. 1\frac12\:m
B. 2m
C. 2\frac12\:m
D. 2\frac23\:m
E. 3m