If a test of hypothesis has a type i error probability of .05, it means that if the null hypothesis is true,
(a) you don't reject it 5% of the time if the null hypothesis is true
(b) you reject if 5% of the time if the null hypothesis is false
(c) you don't reject it 5% of the time if the null hypothesis is false
(d) you reject it 5% of the time