Answer:
d) 50
Step-by-step explanation:
The frequency, that in this case means <em>absolute </em>frequency, means the total amount of subjects that vote for each candidate (not the proportion, that would correspond to the relative frequency).
If the distribution is uniform and we have 3 categories or classes, the three of them should have the same frequency.
The sample size is: 40+60+50=150.
If we have 3 classes, and the distribution is uniform, we should have a frequency for each class of 150/3=50.