Final answer:
The question does not provide enough information to determine the number of squares that will balance 1 rectangle using a pan balance.
Step-by-step explanation:
To determine the number of squares that will balance 1 rectangle using a pan balance, we need to look at the information given in the question. Unfortunately, the question does not provide any specific information about the squares and rectangles or how they are related to each other. Therefore, we cannot determine the correct answer from the options given (a. 1, b. 2, c. 5, d. 13).