In a common-size Balance Sheet, total equity and liabilities are assumed to be equal to:

100

The correct answer is option 3- 100.

Choose a common base (as 100). For example, revenue from operations may be taken as base (100) in case of statement of profit and loss and total assets or total liabilities (100) in case of balance sheet. It presents each item is expressed as a percentage of total liabilities and equity, facilitating comparison across periods or companies.