Concept:The series follows the number of letters in each word.
Explanation:Count the letters of each word in order.
Pension =
7 letters.
Aptitude =
8 letters.
Captain =
7 letters.
Tropical =
8 letters.
Survive =
7 letters.
The pattern is
7,8,7,8,7,..., so the next word must have
8 letters.
Check the options:
Parrot =
6 letters, so it is incorrect.
Apply =
5 letters, so it is incorrect.
Trap =
4 letters, so it is incorrect.
Tetrapod =
8 letters, so it fits the pattern.
Therefore, the missing word is Tetrapod.
Answer:The correct alternative is D. Tetrapod.