The proposed mechanism for a reaction is: Step 1: A + B X (fast) Step 2: X + C Y (slow) Step 3: Y D (fast) What is the overall reaction? A. A + B + C D B. A + X Y + D C. A + B Y D. A + Y D

A. A + B + C - -> D

Explanation:

Step 1: A + B - -> X (fast)

Step 2: X + C - -> Y (slow)

Step 3: Y - -> D (fast)

To obtain the overall reaction, we have to sum up the reactants and products of all step and eliminate the intermediates.

Reactants:

A + B + X + C + Y

Products:

X + Y + D

So we have;

A + B + X + C + Y - -> X + Y + D

Upon elimination of intermediates, we have;

A + B + C - -> D

The correct option is A.