CGPSC Prelims CSAT 2014 Solved Paper 2

Concept:The series follows a fixed gap between the positions of consecutive letters in the alphabet.Explanation:Write the alphabet positions of the given letters:$X=24,\ T=20,\ ?=16,\ L=12,\ H=8,\ D=4$.Each term decreases by $4$:$24-4=20$$20-4=16$$16-4=12$$12-4=8$$8-4=4$The missing position is $16$, which corresponds to the letter $P$.Since $P$ is not given in the options, the correct choice is "None of these".Answer:The missing letter is $P$, so the correct option is E. None of these.