Final answer:
When a sharply hit ball is fielded by the shortstop, advance to second base, ensuring you avoid being doubled off if the ball is caught.
Step-by-step explanation:
As the runner on first base when a sharply hit ball goes to the shortstop, you should attempt to advance to second base, but only after making sure the ball isn't caught for an out. If the shortstop catches the ball on the fly, you must return to first base to tag up before advancing, to avoid being doubled off first base. If the ball is hit on the ground and the fielder goes for a play at second base, you should try to run directly to second base without hesitation to avoid being forced out. In either case, progressing beyond second base usually depends on subsequent plays or errors. It's important to watch the coaches for signs and stay alert during the play to make smart base running decisions.