Which subordinating conjunction correctly completes this sentence? mandy practiced karate every day, she failed to beat her final opponent.

The correct answer is "however".

Explanation:

In the example provided, we need a conjunction that expresses contrast.

Mandy practiced karate every day; however, she failed to beat her final opponent.

In order to link the two independant clauses into a compound sentence, the adverb "however" or "nevertheless"can be used and are correct.

If we want to change an independant clause by a subordinating one, the sentence would be the following (also expressing contrast):

Even though Mandy practiced karate every day, she failed to beat her final opponent.

fiction/fantasy

explanation:

we need to see the paragraphs in order to answer this.