A body floats in a liquid contained in a beaker. The whole system falls freely under gravity. The upthrust on the body due to the liquid is
zero
equal to the weight of the liquid displaced
equal to the weight of the body in air
equal to the weight of the immersed portion of the body.
For a body falling freely under gravity, the effective value of g is zero. Hence upthrust is zero. Hence the correct choice is (a).