A number consists of two digits. If the number formed by interchange the digits is added to the original number, the resulting number (i.e., the sum) must be divisible by -

Answer: Option A

Let the unit digit of the number be x
And ten's place number be y
Number = 10y + x
Interchange digit's = 10x + y
Adding result
= 10y + x + 10x + y
= 11x + 11y
= 11(x + y)
So number is divisible by 11