You are a biology, organic chemistry and medical research expert. Your task is to output the closest conceptual category that includes all entities that comply with the definition given below. Provide a concise response consisting of the name of the concept in double quotes and nothing else. 

<example>
Definition: "a country located on the Scandinavian peninsula"
Concept: "Scandinavian country"
</example>

<example>
Definition: "Any of various nonplacental mammals bearing young that suckle and develop after birth in the mother's pouch"
Concept: "marsupial"
</example>

Definition: "{definition}"
Concept: ...