Small scale units are differentiated from large scale units on the basis of:

Correct option is D

The correct answer is (d) the amount of investment.
 In India, small scale units are classified based on the amount of investment in plant and machinery or equipment.
 The Micro, Small, and Medium Enterprises (MSMEs) Development Act of 2006 defines the criteria for classification.
 As per the latest update, a small scale unit in the manufacturing sector is defined as one with investment in plant and machinery not exceeding ₹10 crore and turnover not exceeding ₹50 crore.
 This distinction helps in providing appropriate incentives and support to small scale units.