A hospital in Mumbai conducted a study to compare the mean systolic blood pressure reduction (in mmHg) following two antihypertensive regimens. Group A (n=25) received atenolol monotherapy with mean reduction of 18 mmHg (SD=6 mmHg), while Group B (n=25) received atenolol plus amlodipine with mean reduction of 24 mmHg (SD=7 mmHg). Both groups were independent, and the data were normally distributed. The researcher wants to test if the combination therapy produces significantly greater blood pressure reduction. What is the appropriate test and the most likely outcome at p<0.05?