The period of how many month/months must elapse between two calls.

The correct answer is Option (2) → 1 month

"Calls are to be made as per the provisions of the articles of association. Where there is no articles of association of its own, the following provisions of Table A will apply:

(a) A period of one month must elapse between two calls;

(b) The amount of call should not exceed 25% of the face value of the share;

(c) A minimum of 14 days’ notice is given to the shareholders to pay the amount; and 

(d) Calls must be made on a uniform basis on all shares within the same class.