Final answer:
Organisms are classified into three domains (Bacteria, Archaea, and Eukarya) and four kingdoms (Protista, Plantae, Fungi, and Animalia) by most scientists.
Step-by-step explanation:
The classification system used by scientists to organize living organisms into groups is characterized by a hierarchy that includes both domains and kingdoms. According to the most widely accepted system used by biologists, all life forms can be classified into three domains: Bacteria, Archaea, and Eukarya. Each of these domains contains multiple kingdoms, where Eukarya consists of kingdoms like Protista, Plantae, Fungi, and Animalia. Considering this, the correct answer to the student's question is that most scientists classify organisms into four kingdoms and three domains.