Step 1: Concept of revaluation.
Revaluation gains and losses arise when the assets and liabilities of a partnership are revalued at the time of a partner's retirement.
Step 2: Distribution of revaluation gains and losses.
At the time of retirement, revaluation gains and losses are shared by the remaining partners in the ratio of their profit-sharing ratio.
Step 3: Conclusion.
Thus, the correct answer is (A) By the remaining partners.
Final Answer:
\[
\boxed{\text{By the remaining partners}}
\]