Use the Following Information for Questions

Multiple Choice

Use the following information for questions:
A student doing an internship at a large research firm collected the following data, representing all of the studies the firm had conducted over the past 3 years.
-What is the probability that the study used randomization, if we already know that the study was a retrospective observational study?

A) 0.1167
B) 0.2333
C) 0.26
D) 0.3111