A prime number between 10 and 40 remains unchanged if its digits are reversed. The square of such a number is

The correct answer is (d).

A prime number is a natural number greater than 1 that is not a product of two smaller natural numbers. A number that remains unchanged if its digits are reversed is called a palindromic number.

The only palindromic prime number between 10 and 40 is 111. However, the square of 111 is 12321, which is not a prime number.

Therefore, the square of a prime number between 10 and 40 that remains unchanged if its digits are reversed is not a prime number.