In uniform circular motion, an object moves in a circular path at a constant speed. Acceleration refers to the rate of change of velocity. Option 1 states that the direction of acceleration is along the direction of motion. This is incorrect because in uniform circular motion, the direction of motion is constantly changing as the object moves around the circle.

Option 2 states that the direction of acceleration is tangent to the circle at the point of observation. This is the correct answer. The acceleration always points towards the center of the circle and is perpendicular to the velocity vector. At any given point on the circle, the tangent line represents the direction of motion, and the acceleration is perpendicular to this tangent line, pointing towards the center of the circle.

Option 3 states that the direction of acceleration is in the same direction as the velocity vector. This is incorrect because acceleration is always perpendicular to velocity in uniform circular motion.

Option 4 states that the direction of acceleration is perpendicular to velocity. This is the correct answer, as explained above.

Therefore, the correct answer is option 4.