The pressure angle of a cam depends upon

Answer: Option D

Option A: Offset between center lines of cam and follower
The pressure angle in a cam mechanism is influenced by the offset between the center lines of the cam and follower.
This offset changes the geometry of contact, which in turn affects the pressure angle.

Option B: Lift of follower
The lift of the follower, or the maximum displacement of the follower, also impacts the pressure angle.
A larger lift generally results in a greater pressure angle as the cam profile must be adjusted to achieve the desired lift.

Option C: Angle of ascent
The angle of ascent is the angle over which the cam raises the follower to its maximum position.
A steeper or larger angle of ascent increases the rate of lift, which also affects the pressure angle.

Conclusion:
The correct answer is Option D: All of the above.
The pressure angle of a cam depends on the offset between the cam and follower, the lift of the follower, and the angle of ascent, as all these factors influence the cam profile and contact geometry.