Choose the correct statement for the first Brillouin zone in two dimensions:
A. The region in k space that the electrons can occupy without being diffracted is called the First Brillouin zone.
B. For k<\(\pi\)/a electrons can not move freely in any direction inside the square without being diffracted.
C. For k = \(\pi\)/a electrons are prevented from moving in the x or y directions due to diffraction.
D. For k>\(\pi\)/a electrons can move perpendicularly inside the square.
Choose the correct answer from the options given below: