The sacrifice of one or more partners be the gain of...........in the partnership firm.

One or more

The correct answer is option 2- One or more.

The sacrifice of one or more partners be the gain of one or more partners in the partnership firm.

The sacrifice by a partner is equal to:
Old Share of Profit of a partner – New Share of profit of a Partner
Gain by a partner is (new- old) share
So, sacrifice is equal to the gain of others.