Complete the sequence: c, a, d, b, e, ___, f, d, g

To determine the missing element in the sequence, let's analyze the pattern presented. The letters appear to be organized in an alternating fashion.

First, we can separate the sequence into two distinct sub-sequences based on their positions. The first sub-sequence includes the letters at the 1st, 3rd, 5th, and 7th positions: c, d, e, f. Notice that this sub-sequence is in alphabetical order, continuously moving one letter forward (c to d, d to e, e to f).

Now, let's look at the second sub-sequence which encompasses the letters at the 2nd, 4th, and 6th positions: a, b, and the unknown value. Following the pattern, the first letter is 'a', and the next letter is 'b', indicating that the next letter should logically follow as 'c'.

Completing this pair provides clarity: the unknown letter in the sequence should be 'c' making it an extension of the observed pattern. The placement of 'c' is consistent with the alternating alphabetical sequence being established.

Therefore, the answer 'c' is supported by the pattern of the sequence.