Final answer:
Heat causes weathering through the process of thermal expansion and contraction, where the top layers of rock repeatedly expand and contract causing them to crack and break away, as correctly described in option 'd'.is the correct answer.
Step-by-step explanation:
Heat causes weathering in various ways, contributing to the breakdown of rocks. The correct option that explains how heat causes weathering is 'd. the top layers of rock repeatedly expand and contract due to fluctuating temperatures as the inner layers remain constant. The top layers crack and peel off over time.' This process, known as thermal expansion and contraction, occurs because the outer layers of rock experience greater temperature fluctuations than the inner layers. As a result, the outer layers tend to expand with heat and contract when temperatures drop, causing cracks to form and eventually leading to pieces breaking away from the main rock body.
This process is distinct from the creation of metamorphic rocks, which involves recrystallizing minerals under heat and pressure, a process that typically takes place deeper within the Earth's crust. However, both processes signify the influential role of heat in transforming rocks. In the context of weathering, heat induces physical changes at or near the Earth's surface, facilitating the breaking down of rocks through repeated expansion and contraction.
Additionally, the role of water in weathering—as a transporter of rock fragments and a contributor to chemical weathering—is key in shaping the lithosphere. Processes like the water cycle are governed by heat from the sun, which drives water to evaporate and later precipitate, further illustrating the interplay of heat and geologic processes on Earth's surface.