Which revision of this sentence uses an absolute phrase?

The swimmer dove into the pool.

A. The swimmer, her shoulder injury finally healed, dove into the pool.

B. Feeling good, the swimmer dove into the pool.

C. Before she started doing laps, the swimmer dove into the pool.

D. The swimmer, having just finished stretching her shoulder, dove into the pool.

Answer: A. The swimmer, her shoulder injury finally healed, dove into the pool.

The absolute phrase is her shoulder injury finally healed

When the noun and the participle that comes after it form an independent clause, the clause can be called an absolute phrase.

An important clue is that the subject of the independent clause (her shoulder) is different of the subject of the other clause (the swimmer).