Product of two natural numbers is 3. Then, the sum of reciprocals of their squares is Choose the correct option.
A) 10 / 9  B) 1 / 289  C) 290 / 90  D) 290 / 19  E) none of these

Rationale: "explanation : if the numbers are a , b , then ab = 3 , as 3 is a prime number , so a = 1 , b = 3 . 1 / a 2 + 1 / b 2 = 1 / 1 ( 2 ) + 1 / 3 ( 2 ) = 10 / 9 option a"
Answer: A