80 adults, 40 women and 40 men were asked to hold an ice cube for 3 minutes and encouraged to curse if they were experiencing too much pain. the outcome (the response) is a measure of the cortisol at the conclusion of the painful experience (lower indicates higher pain tolerance) as measured by a medical expert who did not know the research question. here are the summary statistics of cortisol data:

sample size (n) mean (y) sd (s)
females 40 419 5.5
males 40 422 3.5
which of the following justifies why we can safely use the two-sample t-test in this case?

the two samples are independent and both sample sizes are larger than 30.

the two samples are independent.

the two samples are both larger than 30.

the medical expert did not know which group each participant was assigned to and was blind to the hypotheses of the study

all of the above.