Integers Properties

[BTGmoderatorRO]

If a is an even integer and b is an odd integer which of the following must be an odd integer :

A. a/b
B. ab
C. 2a+b
D. 2(a+b)
E. 3a/b

OA is C

What is the concept of Odd and Even here? An Expert view is needed.Thanks

[GMATWisdom]

If a is an even integer and b is an odd integer which of the following must be an odd integer :

A. a/b
B. ab
C. 2a+b
D. 2(a+b)
E. 3a/b

OA is C

What is the concept of Odd and Even here? An Expert view is needed.Thanks

Let us try the options one by one
A. a/b can be an integer or a fraction hence ruled out
B. ab prodct of even and odd is always even hence ruled out
C. 2a+b shall always be odd because even plus odd is always odd.
Hence option C ic correct.