Which of the following statement about cells is true?

A tissue is defined as a group of similar cells performing a particular function, so cells of a tissue have similar structure. Cells vary widely in shape (round, oval, elongated, branched, etc.) and size (e.g., nerve cells are very long, RBCs are small). Not all cells have a true nucleus—prokaryotic cells like bacteria and mature mammalian RBCs lack a true nucleus. Hence statement (2) is correct.