In plants, the cells of meristematic tissue undergo a process wherein they lose their ability to divide, take up a permanent shape and size, and specialise to perform a specific function. What is this process known as?

Given below are two statements: one is labelled as Assertion (A) and the other as Reason (R). Assertion (A): Collenchyma provides mechanical support to growing parts of plants. Reason (R): Its cells have unevenly thickened cell walls at the corners. In light of the above statements, choose the most appropriate answer:

Which of the following tissues remains alive at maturity and is primarily responsible for storage?