The main source of revenue for 'not for profit organisation' is:

Subscription from members

The correct answer is option 3- Subscription from members.

Subscription is a membership fee paid by the member on annual basis. This is the main source of income of not for profit orgnisations. Subscription paid by the members is shown as receipt in the Receipt and Payment Account and as income in the Income and Expenditure Account. It may be noted that Receipt and Payment Account shows the total amount of subscription actually received during the year while the amount shown in Income and Expenditure Account is confined to the figure related to the current period only irrespective of the fact whether it has been received or not.