Which is a comma splice?

Question

Two great ballet dancers, Anna Pavlova and Vaslav Nijinsky, began their careers in St. Petersburg.

Anna Pavlova and Vaslav Nijinsky, both great ballet dancers, began their careers in St. Petersburg.

Two great ballet dancers began their careers in St. Petersburg, they were Anna Pavlova and Vaslav Nijinsky.

The great ballet dancer Anna Pavlova began her career in St. Petersburg, as did Vaslav Nijinsky, another great dancer.

Answer 1

Two great ballet dancers began their careers in St. Petersburg, they were Anna Pavlova and Vaslav Nijinsky.