Explanation:

- Statement 1: Since \( p \) is odd and \( r \) is even, \( (p - r) \) is odd. Hence, \( (p - r)^2 \) is odd. \( qs \) is even because \( s \) is even; therefore, the product \((p - r)^2 (qs)\) is even.

- Statement 2: \( (q - s) \) is odd (since \( q \) is odd and \( s \) is even). As \( s \) is even, \( (q - s) q^2 s \) is even because any number multiplied by an even number is even.

- Statement 3: Since both \( q + r \) and \( p + s \) are sums of an odd and an even integer, they are odd. Thus, \( (q + r)^2 (p + s) \) is odd.

- Given the explanations:

- Option 1 (1 and 2 only) is incorrect.

- Option 2 (2 and 3 only) is incorrect.

- Option 3 (1 and 3 only) is incorrect.

- Option 4 (1, 2 and 3) is correct.