A researcher has developed a new drug designed to reduce blood pressure. In an experiment, 21 subjects were assigned randomly to the treatment group and received the new experimental drug. The other 23 subjects were assigned to the control group and received a standard, well-known treatment. After a suitable period, the reduction in blood pressure for each subject was recorded. A summary of these data is:
Sample size
Sample mean Sample S.D
Treatment group (new drug)
Control group (old drug)
21
23.48
8.01
23
18.52
7.15
The researcher suspects that the new drug results in greater average reduction in blood pressure than the old drug does. Based on these data, the computed t statistic is:

a. 1.84
b. 2.16
c. 2.31
d. 4.7