Answer:
Option A
Explanation:
Complete question
Dr. Portillo is conducting a study in order to test a causal hypothesis. What type of study must she conduct?
a. an experiment
b. a case study
c. a survery
d. a naturalistic observation
Solution
Hypothesis testing is an statistical analysis that involves testing a sample data to assure the plausibility of the null hypothesis.
After a hypothesis is stated, the next step is to prepare an analysis plan. After the plan is set, experiment methodology must be framed and executed. Once the result of experiment is obtained, it must be validated and hence cross checked with null hypothesis to either accept it or reject it.
Hence, option A is correct