Answer:
The right option is:
D. H0:µ=78 vs. Ha:µ>78.
Step-by-step explanation:
The teacher wants to test the claim that the small class perform better than the large class.
This claim is going to be stated in the alternative hypothesis. If he want to test if the small class perform better, he means that there is evidence that their score is higher than the larger class. Then, he will test the claim that the true mean of the small class is higher than 78 (μ>78).
The null hypothesis will state that there is no significative better performance from the small class (μ=78).
Then the right option is:
D. H0:µ=78 vs. Ha:µ>78.