When performing hypothesis tests,

small P-values generally support the null hypothesis.

P-values are computed assuming the null hypothesis is correct.

a test statistic measures the difference between the data and what is expected if the null hypothesis is correct.

both (a) and (c) are true.

both (b) and (c) are true.

Option b is correct: P-values are computed assuming the null hypothesis is correct, and a test statistic measures the difference between the data and what is expected if the null hypothesis is correct.