Product of two natural numbers is 19. Then, the sum of reciprocals of their squares is
Options:	A) 290 / 289	B) 1 / 289	C) 290 / 90	D) 362 / 361	E) none of these

Rationale: explanation : if the numbers are a , b , then ab = 19 , as 17 is a prime number , so a = 1 , b = 19 . 1 / a 2 + 1 / b 2 = 1 / 1 ( 2 ) + 1 / 19 ( 2 ) = 362 / 361 option d
Answer: D