Which type of cell is specialized for contraction?

Muscle cells are specialized for contraction due to their unique structure and function. They contain a high concentration of contractile proteins called actin and myosin, which enable them to shorten and generate force when stimulated. This characteristic is essential for various bodily functions, including movement, posture, and the functioning of the heart.

In contrast, root hair cells are designed for absorption of water and nutrients from the soil, nerve cells are specialized for transmitting electrical signals throughout the body, and stem cells are undifferentiated cells capable of developing into different cell types. Each of these other cell types serves distinct roles that are not related to contraction. Therefore, muscle cells are the most appropriate answer, as their entire function revolves around the ability to contract effectively.