Correct answer
D. Birds
Explanation
Birds is the correct answer. Review the question and compare it with the other choices to remember this fact for future exams.
Antares is of the largest known ___________?
Mach number is used in connection with the speed of___________?
Earthquake waves travel faster in __________?
The term PVC used in the plastic industry stands for______________?
Atmospheric pressure is the force (per unit-area) perpendicular to a unit-area of planetary surface, as determined by _________.
The Scientific Study of Caves are know as _________ ?