Answer:
c. complementarity and expansion
Step-by-step explanation:
When reasons for using mixed methods in a published study are given, the most frequently given reasons are "complementarity and expansion."
This is based on the fact that with Complementarity, the results from one method are utilized to expand, detail, or illustrate results from another method.
While at the same time, Expansion allows the extent and the whole size of the research to be extended by using several methods for various lines of inquiry.
In other words, because Complementarity and expansion gives research work the necessary body of knowledge to base on, that is the expanded research and the results to deliver adequate and required knowledge.