Let us evaluate the given statements. A, A number is divisible by 9 if and only is it ends in 3. 23/9 is not divisible. FALSE
B. A quadrilateral is a square if and only if it has four right angles. A rectangle is a quadrilateral with four right angles, but it is not a square. FALSE
C. The sum of two integers is positive if and only if the two integers are positive. 12 + (-10) = 2 (positive). FALSE
D. A number is an even number if and only if it is divisible by 2. Thi is true by definition. TRUE
