Which factor is least likely to affect the results and interpretation of a functional MRI? cancerous growth
prescription medication
a sinus infection
caffeinated soda

None of the given options is correct. The correct solution is "Sprained ankle".

Explanation:

Brain activation is assessed by functional MRI via identifying causes an increase in blood flow. The assumption that brain blood flow and neural activity are linked is the basis of this methodology.MRI allows excellent visualization of the structure of the ankle, allowing ligament defects and their related osteochondral including tendon disorders to be correctly identified. In patients with such an uncertain psychiatric history although with equivocal otherwise complicated psychiatric exams, MRI can be particularly useful for early diagnosis of syndesmotic lesions.  

All those other alternatives are not linked to a working MRI. Then the option above is appropriate.

only b