Final answer:
The correct answer is C) Moreover.
Step-by-step explanation:
The correct answer is C) Moreover.
The word 'moreover' is used to add another point or idea to what has already been mentioned. In this case, the fact that Karen is a competitive horseback rider is already known, and the word 'moreover' is used to introduce the additional information that she will be competing in the World Equestrian Games.
For example, you could rephrase the sentence as follows: Karen is a competitive horseback rider. Moreover, she will be competing in the next World Equestrian Games.