At maximum height in projectile motion, v and a are

Explanation

(d) At maximum height v=0 (Correct): This is the correct answer. At the peak of its trajectory, the projectile momentarily stops its upward motion before starting to fall back down. Therefore, its velocity at this point is zero. The acceleration, however, remains downward due to gravity and is not affected by the momentary change in velocity.Incorrect Options Explanation:(a) Parallel (Incorrect): At the maximum height, the velocity is zero, so it cannot be parallel to the acceleration, which is always downward due to gravity.(b) Perpendicular (Incorrect): While the velocity is perpendicular to the displacement at the maximum height (since the object changes direction), it is not perpendicular to the acceleration.(c) Anti-parallel (Incorrect): Similar to (a), the velocity is zero at the maximum height, meaning it cannot be anti-parallel to the acceleration which remains downward.