A population of 100 butterflies living on an acre of land loses three-quarters of its members when a sudden freeze in the spring occurs just after they emerge as caterpillars. This population has undergone a reduction in population size due to

The correct answer is - a density independent factor.

Explanation:

Any external cause or change that leads to the change in the size of a population regardless of the density of the particular population known as a density independent factor in ecology.

Density independent factors are the factors that are not affected by the size of the population size of the species such as weather, climate and natural disasters.

Thus, the correct answer is -  a density independent factor.

[content deleted] - user123802726recklesschicken

answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.