Explanation:

- Option 1: 1 year

- The Indian Constitution doesn't allow the Vice President to officiate as President for more than a year. This option is incorrect.

- Option 2: 6 months

- *Your answer is wrong.*

- The Vice President can act as President for a maximum period of six months while arrangements for conducting the Presidential election are made.

- Option 3: 4 months

- This duration is shorter than what is allowed. Hence, it's incorrect.

- Option 4: 9 months

- This duration exceeds the allowed maximum period. It is incorrect.

- The Vice President steps in as Acting President when the office of President is vacant. However, an election for a new President must be held within six months.