An unlearned behavior directly linked to a stimulus that is carried to completion once initiated and is essentially unchangeable is see concept 51.1 (page 1138)

A fixed action pattern is a behavior that is carried out to completion once started, regardless of changes in the original stimulus and the sequence is unchangeable. The unlearned behavior of fixed action patterns are triggered by a type of external stimulus that start off a particular organism.

the cell theory states that all living things including animals, as well as plants, are made of cells.

currents is the correct answer.