Correct option is C
In screw threads, lead is the distance a thread advances in one full rotation of the screw, while pitch is the distance between corresponding points on adjacent threads.
The relationship between lead (L) and pitch (P) is given by:
Lead = Pitch × Number of Starts
· If Lead = Pitch × 1, it is a Single Start Thread.
· If Lead = Pitch × 2, it is a Double Start Thread.
· If Lead = Pitch × 3, it is a Triple Start Thread.
Applications of Double Start Threads:
· Lead screws in lathes and CNC machines.
· Power transmission in jackscrews and bottle jacks.
· High-speed fastening systems.
