This test measure the ability of the candidate in word building. Here, the words are built either by prefixing (before) or suffixing (fixing at the end) new letters or taking off from or adding new letters to the body of the words.
Example: Imagine a single letter which when added to the body of the following words forms entirely new words;
Solution: The candidate will see that if the word R is added to each of the given words then new words will be;
FIRST, TRICK, HEART, BURST
Hence the answer is R.