Rounding the sprint course in Osrblie, Slovakia, on Friday, American Chloe Levins didn’t let her mind wander to what could be. She had cleaned her first prone stage, which put her in contention for a top 10 among the field of 92 in the youth women’s 6-kilometer sprint, and another shooting stage without a miss could mean the race of her life in her second race at the 2017 International Biathlon Union (IBU) Youth World...