How do most single-celled organisms meet the challenge of reproducing? Choose the BEST response! HELP ASAP

The first supersonic flight was 1947. it was just above the speed of sound. which altitude would you expect captain yeager to have used for his flight? a) sea level b) 1000m c) 13,700m (within altitude used by commercial planes today) d) 85,000m (where meteor showers originate) will mark brainlist