For a hypothesis comparing two population means, H0: 1 2, what is the critical value for

Question:

For a hypothesis comparing two population means, H0: μ1 ≤ μ2, what is the critical value for a one-tailed hypothesis test, using a 5% significance level, with both sample sizes equal to 13? Assume the population standard deviations are equal.
a. ±1.711
b. +1.711
c. +2.060
d. +2.064