IMO: I only

ab^2/c is a positive even integer
I. ab is even : since ab^2 is even integer the either a or b or both have to be even implies ab is even, both a & b cannot be odd
either case ab will be even...true always
II. ab > 0 not necessary true, ab^2/c positive implies a,b^2 & c are all positive but we cannot say about b...it cud be positive or negative
III. c is even...not necessarily true, c cud be odd if a is odd as ab^2 is an integer.
if b is even : a cud be even leads to c even; OR a is odd leads to c odd or even
if b is odd, then a is even & c cud be even or odd

Good work!

OA I only

well .. why not I and II ?

ab has to be positive because .. if b is negative .. a can be negative and c can be negative. Am I missing something ?

- pradeep

pbanavara wrote:well .. why not I and II ?

ab has to be positive because .. if b is negative .. a can be negative and c can be negative. Am I missing something ?

- pradeep

you just answered yourself.

The question is what MUST be true.

if A was negative and B was positive, then ab < 0,

but if C was negative, the statement is true again that the value is positive.

Therefore, it does NOT have to be true at all times.

hwiya320 wrote:

pbanavara wrote:well .. why not I and II ?

ab has to be positive because .. if b is negative .. a can be negative and c can be negative. Am I missing something ?

- pradeep

you just answered yourself.

The question is what MUST be true.

if A was negative and B was positive, then ab < 0,

but if C was negative, the statement is true again that the value is positive.

Therefore, it does NOT have to be true at all times.

Oh man .. missed that MUST clause .. danka

A little confused here.....

must be = should necessarily be true ??
or
must be = could be true??

I only

i did the MGMAT may (dunno why it clicked)

ab^2 = c * even

(note how doing this doesn't violate the rule that c could be 0, because the question doesn't test for that here).

so for RHS to be correct, LHS must be even as well. II is out since b's sign can be hidden coz of the square. c doesn't have to be even for RHS to be even, because anything multiplied by even will be even.