The answer is C.
The next two letters are likely C & U. There are at least 2 patterns in these letters. FIrst is the list of vowels that make up every other letter. Then the letters alternate from the ends of the alphabet. If there is a Z, a B, then a Y, then C would likely be next, and then X. But there would be whatever vowel in sequence next.
The next letter in the series w s p l h will be different depending on the pattern that you are using. If the pattern is skipping letters in a 3 2 3 3 2 pattern, the letter will be e.
R All other brackets all have 3 steps between a letter to the next.
c is next
c is next
A single number, such as 12848384 does not make a series.
The next letter is D. The pattern is every fourth letter. Ie. a b c D e f g H i j k L m n o P and so on...
I'm convinced that 3,840 is.
the next one is 1234
They would both be 25.
The next (and last) letter is C. Just as a countdown counts backwards, this series is "countdown" spelled backwards.
65 followed by 129
A single number, such as 364758 does not describe a sequence, nor a series.