Which of the following best describes 'massive' in terms of physical characteristics?

The term "massive" refers primarily to something that has great weight or bulk. When describing physical characteristics, "massive" conveys a sense of substantial size and density, leading to the expectation that the object is heavy. This definition aligns with the chosen answer, as the heaviness often accompanies items deemed massive.

The other options describe characteristics that do not align with the concept of being massive. For instance, "lightweight" contrasts directly with the notion of heaviness. "Extensive" refers to a large area or range but does not imply weight. "Compact" suggests a small, tightly packed structure, which is the opposite of what is meant by massive. Thus, in the context of physical characteristics, the best descriptor for "massive" is heavy.