The correct answer is option 'C' - Partially true.

Explanation:
When a new partner is admitted into a partnership, certain adjustments need to be made in the capital accounts of the old partners. These adjustments are made to ensure that the capital accounts of the old partners reflect their true positions after the admission of the new partner.

Contingency Reserve:
A contingency reserve is created to meet unforeseen future liabilities. It is usually created by setting aside a portion of profits. When a new partner is admitted, the contingency reserve is credited to the capital accounts of the old partners in their old profit-sharing ratio. This means that the old partners will receive their share of the reserve based on their respective profit-sharing ratios prior to the admission of the new partner.

Profit and Loss Account (Credit) Balance:
A credit balance in the Profit and Loss Account represents undistributed profits. When a new partner is admitted, the credit balance in the Profit and Loss Account is also credited to the capital accounts of the old partners in their old profit-sharing ratio. This ensures that the old partners receive their share of the undistributed profits.

Deferred Revenue Expenditure Account:
Deferred revenue expenditure refers to expenses that provide benefits over a period of time. These expenses are not fully written off in the year they are incurred but are spread over a number of years. When a new partner is admitted, the balance in the Deferred Revenue Expenditure Account is also credited to the capital accounts of the old partners in their old profit-sharing ratio. This is done to ensure that the old partners receive their share of the benefits from the expenses incurred.

In conclusion, the contingency reserve, credit balance in the Profit and Loss Account, and the balance in the Deferred Revenue Expenditure Account are credited to the capital accounts of the old partners in their old profit-sharing ratio at the time of the admission of new partners. However, it is important to note that this is only partially true as there may be other adjustments made to the capital accounts of the old partners depending on the specific circumstances of the admission of new partners.