Answer
(a) the vector field in (C)
(b) the vector field in (B)
Work Step by Step
(a) According to the universal theory of gravitation, planet pulls other planet toward itself. So, the vector fields in Figure 16 that describes this fact is (C).
(b) According to the electrostatic theory, positive charge is pulled toward the negative charge. Since $Q$ represents a negative test charge, $P$ is pulled toward $Q$. The vector fields in Figure 16 that describes this fact is (B).
