Final answer:
If the president disputes a declaration of disability, Congress must decide if the president is unable to discharge the duties of office within 21 days. If they fail to reach a two-thirds majority, the president resumes their duties.
Step-by-step explanation:
The question is about the process of declaring a president disabled or incapacitated. According to the provided information, if the president disputes a declaration of disability, the decision falls upon Congress. Congress must convene within 48 hours if not already in session, and within 21 days they must determine by a two-thirds vote if the president is unable to discharge the duties of office. If unable to reach a two-thirds majority, the president resumes their duties.