which of the following best completed the sequence

C3, H8, M13, R18

no idea, but they are all letters and their place in the alphabet.

To find the pattern in the given sequence, let's take a look at the given letters and numbers:

C3, H8, M13, R18

One approach is to observe the position of the letter in the English alphabet and add it to the number. Let's calculate the letter positions:

C -> 3,
H -> 8,
M -> 13,
R -> 18

Now, let's combine the letter position and the number:

3 + 3 = 6,
8 + 8 = 16,
13 + 13 = 26,
18 + 18 = 36

So, the pattern seems to be adding the letter's position in the alphabet to the corresponding number.

Now, let's find the missing element by applying the pattern.

For the next letter, N, its position in the alphabet is 14. Adding 14 to the corresponding number, which is 23, gives us:

14 + 23 = 37

Therefore, the best completion for the sequence would be N37.