Observe the figur

a. The body sinks deepest in C, less deep in B, and floats in A. So the buoyant force is largest in A, then B and then C; it acts against the weight and pushes the body upward. The gravitational force which acts downward, is thus highest in C, followed by B, followed by A.

b. Liquid A has density equal to the solid. That’s why the gravitational force (weight of body in air) is equal to the buoyant force (i.e. the weight of displaced liquid), and the body floats.