In a certain city each of 6 Bus lines is represented by a colored flag. Each flag consists of either a single color or a pair of two different colors. If each bus lines has a different flag, what is the minimum number of colors needed for the flags. (Assume that the order of colors in a pair on a flag does not matter.)
Choose the most appropriate option.
A) 2	B) 4	C) 3	D) 1	E) 5
C.3:   if we have 3 colors we can choose pairs in 3C2 ways = 3 and single color flags are 3. Therefore total number of flags = 6.   ANS 3.
<result>C</result>
In a certain city each of 6 Bus lines is represented by a colored flag. Each flag consists of either a single color or a pair of two different colors. If each bus lines has a different flag, what is the minimum number of colors needed for the flags. (Assume that the order of colors in a pair on a flag does not matter.)