When Carolus Linnaeus created his classification system in the 1700s, he sorted organisms based on their physical characteristics. In 1990, Carl Woese and his colleagues introduced a new classification system that sorted organisms into three different domains. Which of the following best explains why this change occurred?A. Many of the organisms classified by Linnaeus are extinct, and his classification system was considered outdated.B. Linnaeus' classification system did not account for similar organisms being found in different geographic locations.C. New genetic research showed that organisms with similar characteristics were not related to each other.D. Organisms were discovered that belonged in more than one of Linnaeus' kingdoms, based on physical appearance.

Carolus Linnaeus is known for his contribution to the Two kingdom classification system which was based on the morphological characteristics. But with the advancement in the technology and gain of knowledge in an interdisciplinary field led to the change in the classification system.

Carl Woese proposed 6 kingdom classification in the 1970s which was very different from the system of Linnaeus. The system was based on the study of the genes which proved that the morphology of different related organism could be the same if they could face the same natural pressure.

Thus, Option-C is correct.