In a linear Simple Harmonic Motion (SHM)
(A) Restoring force is directly proportional to the displacement.
(B) The acceleration and displacement are opposite in direction.
(C) The velocity is maximum at mean position.
(D) The acceleration is minimum at extreme points.
Choose the correct answer from the options given below:

Analyzing each statement for linear SHM:

(A) Restoring force is directly proportional to displacement: $$F = -kx$$. Yes, $$|F| \propto |x|$$. TRUE.

(B) Acceleration and displacement are opposite in direction: $$a = -\omega^2 x$$. The negative sign means they are always opposite. TRUE.

(C) Velocity is maximum at mean position: $$v = \omega\sqrt{A^2 - x^2}$$, maximum when $$x = 0$$ (mean position). TRUE.

(D) Acceleration is minimum at extreme points: $$|a| = \omega^2|x|$$, which is MAXIMUM at extreme points ($$x = \pm A$$), not minimum. Acceleration is minimum (zero) at the mean position. FALSE.

Correct statements: A, B, and C.

This matches option 3: (A), (B) and (C) only.