The Coach of an Adult Master's Swim Class Selected Eight

The coach of an adult Master's Swim class selected eight swimmers within each of the two age groups shown below.A 50-yard freestyle time is recorded for each swimmer.The resulting times (seconds) are shown below.Which statistical test would you choose to compare the two groups?

A) t-test for independent samples with known variances
B) t-test for independent samples with unknown variances
C) t-test for paired samples
D) z-test for two independent proportions