Question $3(1$ point$)$

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Identify which of the sentences below has an incorrect, unnecessary comma:

Question $3$ options:

She asked me to pick up cat food, litter, a collar, and a new dish.

The transit workers voted to strike and walked off the job.

The small beta, who is fierce to other fish, swims alone in his tank.

The capital of the Dominican Republic, is Santo Domingo.