Answer:
c. 28
Step-by-step explanation:
The degrees of freedom for a t-statistics is given by the following formula:
df = (sample size - 1)*number of experiments.
In this problem, we have that:
15 participants, so the sample size is 15.
Two treatment conditions, so the number of experiments is 2.
So
df = (15 - 1)*2 = 28
So the correct answer is:
c. 28
