Find out the missing letters for the given series from the given alternatives.
$a....abbb...ccccd.....ddccc.....bb....ba$

Study the following arrangement carefully and answer the question given below:
$B, 2, I, J, K, 4, 3, H, 5, E, R, P, 6, N, A, 9, W, 8, T, U, 1, V, D, 7, F$
Four of the following five are alike in a certain way and so form a group based on their positions in the given arrangement. Which is the one that does not belong to this group?

Study the following arrangement carefully and answer the question.
$O, 4, E, J, 5, T, 1, A, M, Q, 3, 8, N, I, K, 7, W, F, 6, S, 9, U, 2, Y, X$
Which of the following is the fourth to the right of the tenth from the right end of the above arrangement?

Choose the correct alternative for the missing term.
$C4X, F9U, I16R, ?$

Choose the correct alternative to complete the series: $ab .... ...b .... ....bbaa$

Find the missing letters for the given series from the given alternatives:
$acc....bc....a....ccbbcc.....$