Organisms are divided into different kingdoms based on differences in their characteristics. Two major characteristics that scientists use to determine which kingdom an organism belongs to are
ability to make food and ability to swim.
OA
OB ability to swim and number of cells.
OC.
ability to fly and size of organism.
OD
ability to make food and number of cells.

A. ability to make food and ability to swim

Explanation:

Living organisms have been grouped into an hierarchical system of classification that begins with the kingdom, which is the most inclusive taxon. Organisms were placed into kingdoms based on two major criteria namely; their nutrition and mobility.

Their nutrition depends on their ability to make food by themselves (autotrophic) or not (heterotrophic) while their mobility depends on their possession of structures for locomotion.

answer: - b cells

explanation: -

so, the b cells mediate their action by identifying the antigens present on the surface of the pathogens and then producing antibodies in return to mediate its effect.