Assertion: According to steady state hypothesis, in a multistep reaction, the change in concentration with time for reactive intermediates is zero. Reason: The intermediates are so reactive that after a brief initial period their concentrations rise from zero to a small value and remains constant for most of the duration of the reaction. Read the assertion and reason carefully to mark the correct option out of the options given below:

• A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
• B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
• C. If assertion is true but reason is false.
• D. If the assertion and reason both are false.