Which of the following are the principles of 'Scientific Management'?
1. Development of a science of work.
2. Different piece rate.
3. Standardisation of tools and equipments.
4. Scientific selection of workman.
5. Co-operation between managers and workers.
Select the correct answer:

A. 1, 3, 4 and 5

B. 1, 4 and 5

C. 1, 2, 3 and 4

D. All of these

Answer: Option D