Answer:
Yes, because the calls were each randomly assigned a greeting.
Explanation:
It is given that Andrew who works at the call center of an insurance company, decided to conduct a small survey on how to greet the potential customers while calling.
For this, he uses his 500 subsequent calls and he chooses to greet his customers randomly as "Howdy" or "Hiya".
Since the selection bias is ruled out, the calls were randomly assigned for the greetings. Thus the greetings caused a difference in sales.