The two events are mutually inclusive when they can both occur simultaneously. In unicellular organisms growth and reproduction are mutually inclusive, because they have only single cell which performs all the functions for living. For growth to take place, there is nothing such distinct growth as the size of the cell does not become large (every cell has a specific size which it maintains). Ones the unicellular organisms divide, it is considered as cell division as well as reproduction. Basic thing that is required for growth and development to take place is cell division. In single celled organism ones division takes place means it is no longer the same old organisms. So growth and reproduction are not distinct.
In multicellular organisms, specific organs work for reproduction. Growth and development are independent of reproduction and vice-versa. Though they are reproducing, they are not losing their identity and continuous growth and development goes on over all in the body.