Final answer:
After injecting thallium-201 during a stress test, the patient should continue exercising for 1 minute to ensure optimal distribution of the tracer for the assessment of heart function and blood flow.
Step-by-step explanation:
The question pertains to the administration of thallium-201 during a cardiac stress test. After thallium injection, the standard protocol typically requires the patient to continue exercising for an additional minute to ensure optimal distribution of the thallium throughout the cardiac tissue. Therefore, the correct answer is A) 1 minute. This period of continued exercise helps medical professionals in the assessment and visual analysis of the heart function and blood flow, which can be crucial in diagnosing various cardiac conditions.