Answer:
Option D is the correct answer.
Step-by-step explanation:
The speed of sound refers to the distance travelled per unit time by a sound wave as it moves. At 68ยบ F its speed in air is about 343 meters per second, or 767 miles per hour or a kilometer in 2.9 seconds. There are two big factors to be considered: first one is temperature and the material the sound is traveling through, so the last option is the right answer.