Select the option that represents the letters that, when sequentially placed from left to right in the blanks below, will complete the letter series.
\text{ABZ, BCY, CDX, DEW, \_\_\_\_\_\_\_\_}}

Let's break down the series into three separate letter tracks based on position inside each term:
First letter track: A, B, C, D, ...

A+1=B

B+1=C

C+1=D

Next letter: D+1=E

Second letter track: B, C, D, E, ...

B+1=C

C+1=D

D+1=E

Next letter: E+1=F

Third letter track: Z, Y, X, W, ...

Z−1=Y

Y−1=X

X−1=W

Next letter: W−1=V

Combining the results, the next term in the series is EFV.