Methods of production will change if the relative price of inputs change. This is the principle of

The question describes a scenario where producers alter their methods of production by changing the mix of inputs they use in response to changes in the relative prices of those inputs. This is a core concept in economics.

• Substitution refers to the act of replacing one input with another due to changes in their relative costs. If one input becomes relatively more expensive, producers will try to substitute it with a cheaper alternative to maintain efficiency and minimize costs.

Therefore, the principle described is substitution.

The correct option is B.
B) substitution.