Use lookup in dictionary.

Read the sentence and understand the context. They're talking about cooking. So, we can eliminate option (a).
Now, you have (b) and (c). (c) is talking about an action. The given sentence has an action (stir). Hence, it is (b).

Batter: A mixture consisting chiefly of flour, egg, and milk or water and being thin enough to pour or drop from a spoon thi

(b) a liquid mixture