A scientist used a unique two-color code to identify each of the test subjects involved in a certain study. If the scientist found that choosing from among six colors produced enough color codes to identify all but 5 of the test subjects, how many test subjects were in the study? (Assume that the order of the colors in the codes does not matter.)	Choose the correct choice from the following answers:
A) 7  B) 10  C) 15  D) 17  E) 20
If 6 colors have to be divided into groups of 2, the number of unique groupings 6C2 = 6! / (2!)(4!) = 15.   Number of combinations was sufficient to account for all but 5 of the subjects   Number of subjects = 15 + 5= 
<gadget id="calculator">15 + 5</gadget>
<output>20</output>
20.   ANSW20R:20
<result>E</result>
A scientist used a unique two-color code to identify each of the test subjects involved in a certain study. If the scientist found that choosing from among six colors produced enough color codes to identify all but 5 of the test subjects, how many test subjects were in the study? (Assume that the order of the colors in the codes does not matter.)