When a patient with hypertension takes a particular type of blood pressure medication, the effects on the systolic pressure, S(t), can be measured by the following piecewise defined function: S of t is equal to the piecewise function of 145 minus 6 times t if 0 is less than or equal to t is less than or equal to 5 and 115 if 5 is less than t is less than 9 and 52 plus 7 times t if 9 is less than or equal to t is less than or equal to 12 where t is the time, in hours, since taking the medication. Based on the graph of the piecewise function, if the patient takes the blood pressure medication at 7 a.m., in which interval will their systolic pressure be lowest?
1 p.m. to 3 p.m.
4 p.m. to 6 p.m.
7 a.m. to 9 a.m.
10 a.m. to 12 p.m.
