Answer: Option B
:
B
Weight of a body is given by:
$W=mg$
where:
$m:$ Mass of the body
$g:$ Acceleration due to gravity
At the center of earth, acceleration due to gravity is zero. This is because mass of earth is distributed uniformly about this point. For every small part of mass of earth that attracts the body in one direction, we can find another small mass that will attract it in opposite direction with the same force. The net force due to each such pair is zero.
Hence, net force at the center of earth is zero.