The correct answer is: D. Date of his admission into the firm
A minor is a person who has not attained the age of majority, which is 18 years in most jurisdictions. A minor cannot enter into a contract, including a partnership agreement. However, if a minor does enter into a partnership agreement, the agreement is voidable at the option of the minor. This means that the minor can choose to cancel the agreement at any time.
If a minor partner in a firm attains majority and elects to continue as a partner, they will be liable for the debts of the firm from the date of their admission into the firm. This is because, once a minor attains majority, they are considered to have ratified the partnership agreement. Ratification is the act of accepting the terms of an agreement after it has been made. Once an agreement has been ratified, it is considered to be valid and enforceable.
The other options are incorrect because they do not reflect the law on partnerships. Option A is incorrect because a minor cannot enter into a contract, including a partnership agreement. Option B is incorrect because a minor is not liable for the debts of the firm until they attain majority and elect to continue as a partner. Option C is incorrect because a minor cannot decide to be a partner until they attain majority.