Analogy — Cause and effect (physiological vs physical processes): Injury : Pain :: Rotate : ? Select the effect caused by the action, paralleling “injury causes pain”.

Introduction / Context:
Injury typically causes pain. Similarly, rotation (e.g., of paddles/beaters) causes churning. The relation is direct cause→effect.

Why Other Options Are Wrong:

• Matter : Labour — Vague relation.
• Thunder : Lightning — Physical correlation, but lightning causes thunder (not vice versa).
• Grades : Merit — Effect vs cause reversed; merit leads to grades.
• None of these — invalid because a correct mapping exists.

Final Answer:
Rotate : Churning