He was always ……………………….. in performing his tasks, waiting until the last moment to finish them.
In this example, the correct choice is the single word which should stand for the habit of waiting until the last moment to finish a task.
You can guess that the missing word must mean the same as delaying, tardy, procrastinating, lazy etc…
If you look at the given five choices now, it is only the word dilatory that has this meaning and that is the answer.
So, the answer is (A).
GRE : Model Questions Index