One of mary and jose's classmates agreed that the conditions for taking the survey were controlled, but she said that the results were not valid. how would you respond to this classmate?

a) the student is correct; the experiment is not valid because it deals with opinions.
b) the student is incorrect: the experiment is valid because it measures what is says it measures.
c) the student is correct: the survey does not give respondents a chance to write in the preference.
d) the student is incorrect: the experiment is valid because it is consistent in its data collection methods.