The correct answer is: B. Splits into thin sheets along its bedding planes
Slate is a type of metamorphic rock that is formed when shale is subjected to heat and pressure. It is characterized by its ability to split into thin sheets along its bedding planes. This property makes slate ideal for use in roofing, flooring, and other applications where a smooth, flat surface is required.
Option A is also correct, as slate is a metamorphic rock. However, this is not the most distinctive property of slate, and so it is not the best answer to the question.
Option C is incorrect, as slate does not have a smooth surface. In fact, slate is often quite rough, due to the presence of small, embedded crystals.
Option D is also incorrect, as slate does not have good water absorption capacity. In fact, slate is quite resistant to water, which is one of the reasons why it is so popular for use in roofing and flooring.