Observer a Sees a Ruler Moving by in a Relativistic

Multiple Choice

Observer A sees a ruler moving by in a relativistic train and measures its length to be L_A. Observer B moves together with the train and measures the length of the ruler to be L_B. These two results will be such that

A) L_A > L_B.
B) L_A = L_B.
C) L_A < L_B.
D) L_A could be greater or smaller than L_B depending on the direction of the motion.