What is an organelle?

A. the basic building block of living things; the smallest piece of every organism that has all of the characteristics of a living
thing and can perform all life functions

B. one small part in or around a cell that has a very specialized job or function

C. structure, such as a heart or a leaf, made up of different types of tissues that all work together.
D. the smallest unit of an element that can be considered that element; they make up all matter