Step 1: Understanding the Concept:
This is a simple fraction problem. We need to find half of a given quantity. Step 2: Detailed Explanation:
The full recipe requires 4 cups of flour.
The baker wants to make half the recipe, so we need to calculate half of 4.
\[ \text{Flour needed} = \frac{1}{2} \times 4 \text{ cups} \]
\[ \text{Flour needed} = 2 \text{ cups} \]
Step 3: Final Answer:
The baker will need 2 cups of flour. This corresponds to option (B).