The optimum product combination at a given level of resources will be where:

✅ Explanation: The optimum product combination is achieved when the marginal rate of product substitution (MRPS) equals the price ratio of the two products. MRPS is the rate at which a firm can substitute one output for another while keeping the total resource cost constant. In this case(b) ∆y2 /∆y1= Py1/Py2 represents the MRPS, and Py1/Py2 represents the price ratio.