Which of the following is true in respect of 'Product Method' for calculating National Income?-
a) Product Method is also called Value Added Method.
b) Value added is a flow variable.
c) Production of the firm = value added + intermediate goods used by the firm.

a, b and c

The correct answer is Option 1: a, b, and c.

Here's why each statement is true:

a) Product Method is also called Value Added Method: This is correct. Both methods calculate national income by summing the value added at each stage of production.

b) Value added is a flow variable: This is also correct. Value added represents the net output or the additional value created by a firm during the production process. It is a flow variable measured over a specific period, unlike capital stock, which is a stock variable.

c) Production of the firm = value added + intermediate goods used by the firm: This statement is true as well. 

Value added of a firm = Value of production of the firm – Value of intermediate goods used by the firm.

Thus, Value of production of the firm = Value added of a firm +Value of intermediate goods used by the firm. (C is also correct)

Therefore, all three statements (a, b, and c) are true regarding the Product Method for calculating National Income.