A, B and C are partners sharing profits and losses in 5 : 3 : 2. What will be new profit sharing ratio between A and C if B decided to take leave from the firm?

The correct answer is $\boxed{\text{C. }5:2}$.

If B decided to take leave from the firm, the new profit sharing ratio between A and C would be 5:2. This is because A and C would now share the profits and losses equally, as B is no longer a partner.

Option A is incorrect because it does not take into account the fact that B is no longer a partner. Option B is incorrect because it would give A a disproportionate share of the profits. Option D is incorrect because it would give C a disproportionate share of the profits.