From the words or groups of words lettered A to D, choose the words or group of words that best completes each of the following sentences. Mary did her best...

Answer Details

The word that best completes the sentence is "but". "But" is used to connect two clauses, with the second clause usually presenting a contrast or something unexpected with the first clause. In this case, the first clause is "Mary did her best" and the second clause is "failed to reach the pass mark", which presents a contrast with the first clause. Therefore, the sentence can be completed as follows: "Mary did her best but failed to reach the pass mark."