Final answer:
The number of minutes of therapy that must be provided to count as a day of therapy on the MDS is at most seven hours.
Step-by-step explanation:
The correct answer is b. is at most seven hours.
The question is asking about the number of minutes of therapy required to count as a day of therapy on the MDS.
If the number of therapy minutes is more than seven hours, it exceeds the limit for a day of therapy. If the number of therapy minutes is at most seven hours, it qualifies as a day of therapy.