In the 1700s, Swedish scientist Carl Linnaeus developed the first comprehensive system for classifying living things. His system included two kingdoms—animal and plant. In the 1860s, scientists expanded this classification system to three kingdoms. The new kingdom included all single-celled organisms. What name did they give this third kingdom?

Kingdom Protista

Explanation:

Following up to the classification of living things into two broad classification; kingdom animalia and plantae by Carl Linnaeus in the 1700s, in the 1960s, German scientist, Ernst Haeckel proposed a three kingdom classification system which is, Kingdom Animalia, Plantae and Protista. Kingdom protista is to include all unicellular organisms such as fungi, protozoa, bacteria and other microorganisms.

when two people answer a question, a choice will pop up at the top of each persons answer, and it will say mark as brainliest.

hope this : )

explanation:

the answer is either c or d i think its d