Manhattan_ Is the postive integer x odd

[nh8404052006]

Is the positive integer x odd?
(1) x = y^2 + 4y +6
(2) x = 9z^2 + 7z - 10

please explain, thank
OA : B
Source: Manhattan challenge problem

[Vemuri]

Question is asking if x is odd?

Stmt 1: x = y^2 + 4y +6 . We do not know if y is even or odd
If y is odd ==> x = odd+even+even ==> x = odd
If y is even ==> x = even+even+even ==> even
So, this statement is not sufficient

Stmt2: x = 9z^2 + 7z - 10. We do not know if z is even or odd
If z is odd ==> x = odd+odd-even = even
If z is even ==> x = even+even-even = even
This statement is sufficient.

Hence B is the answer.