K What is a doubling time? Suppose a population has a doubling time of 20 years. By what factor will it grow in 60 years? SCO Choose the correct definition of a doubling time below. O A. The time required for each halving in exponential growth. O B. The time required for each doubling in exponential growth. O C. The time required for each halving in linear growth. O D. The time required for each doubling in linear growth. By what factor will population grow in 60 years? (Type exponential notation with positive exponents.)