Final answer:
The correct answer is d. P23 < 400.
Step-by-step explanation:
The correct answer is d. P23 < 400.
To indicate that the limit on production of the company's three products in period 2 is 400, we need to consider the production of Product 3 in Period 2. The correct representation would be P23 < 400, indicating that the production of Product 3 in Period 2 should be less than 400.
Pij represents the production of product i in period j. So, P23 represents the production of Product 3 in Period 2.