Answer: C
Explanation: The apical meristem is a region at the tip of a plant's stem or root that contains a cluster of tiny, unspecialized cells called meristematic cells. These cells are capable of dividing rapidly, allowing the plant to grow in length. As the cells at the tip of the stem or root differentiate and mature, they become specialized for different functions, such as photosynthesis or support. The apical meristem is responsible for the primary growth of a plant, which is the growth in length that occurs during its early stages of development.