Answer & Explanation
The 2nd, 5th and 8th digits of the number 31549786 are 1, 9 and 6 respectively.
The perfect square of a two - digit even number, formed using the digits 1, 9 and 6 is 196. And,
So, the required even number is 14. Clearly, its second digit is 4.
Hence, the answer is (b).