If a, b, c and d are four positive real numbers such that sum of a, b and c is even the sum of b,c and d is odd, then `a^2-d^2` is necessarily

Options

A. odd
B. Even
C. Prime
D. Either (a) or (b)

Answer

A

Explanation

(i) Subtract one condition from another and proceed.
(ii) `(a+b+c)-(b+c+d)=` even-odd
`rArr a-d` is odd.
(iii) `a+d` is also odd.