Final answer:
The phrase 'Mustangs won the tournament' entails that 'The tournament was won by the Mustangs.' It means that the outcome of the event is that the Mustangs were victorious. Options B and C are likely but do not describe the outcome of the tournament as related to the Mustangs winning.
Step-by-step explanation:
The correct answer to the question 'Mustangs won the tournament. This (entails):' is option A) The tournament was won by the Mustangs (bidirectional). This statement is directly implied by the original statement that the Mustangs won the tournament. It's bidirectional because it can be stated either as 'Mustangs won the tournament' or 'The tournament was won by the Mustangs' without changing the meaning. The other options B) The Mustangs were qualified to join the tournament and C) The Mustangs played in the tournament are unidirectional as they imply a one-directional relationship that does not necessarily affirm the outcome of the tournament.
From the statement that the Mustangs won, it's inherently true that they would have had to play in the tournament to win it, which makes option C) a fact but not what the phrase 'entails.' And while option B) is likely true since a team must be qualified to participate, it is not what the original statement implies about the outcome of the tournament.