Consider the sequence ABC_ _ ABC_ DABBCD_ ABCD that follows a certain pattern. Which one of the following…
Consider the sequence ABC_ _ ABC_ DABBCD_ ABCD that follows a certain pattern. Which one of the following completes the sequence?
DACB
CDAB
DCCA
DDCA
Solution
The sequence is built from the repeating block ABCD. Filling the four blanks so that the whole string reads as repeated ABCD blocks gives the blanks as D, D, C, A. The completing group is DDCA.