Consider the following statements regarding cams:

1. Base circle is the smallest circle tangent to the cam profile (contour) drawn from the centre of rotation of a radial cam.

2. Pitch curve is the curve drawn by the trace point assuming that the cam is fixed, and the trace point of the follower rotates around the cam.

3. Pitch circle is the circle passing through the pitch point and concentric with the base circle.

4. The smallest circle drawn tangent to the pitch curve is known as the prime circle.

Which of the above statements are correct?