For the \( C_2v \) point group, the symmetry operations \( E, C_2, \sigma_v, \) and \( \sigma' \) have the following characters for the valid irreducible representations.
- \( E \) (identity operation) has a character of 1.
- \( C_2 \) (rotation by 180°) has a character of -1 for some irreducible representations.
- \( \sigma_v \) and \( \sigma' \) (vertical mirror planes) also contribute characters based on the symmetry of the system.
After performing the necessary character table analysis, the correct answer is (D) 1, −1, −1, −1.
Final Answer:
(D) 1, −1, −1, −1.