Key' is a taxonomical aid used for the identification of organisms. Each statement in key is called a _________.

Options

A. couplet
B. lead
C. both (a) and (b)
D. none of these

Explanation

To solve the question, we need to identify what each statement in a taxonomical key is called. Here’s the step-by-step solution:

1. **Understanding Taxonomical Keys**: A taxonomical key is a tool that helps in the identification of organisms based on their characteristics. It is structured to guide users through a series of choices.

2. **Structure of the Key**: The key is designed based on contrasting characteristics of organisms. These characteristics are presented in pairs, allowing the user to make decisions based on the presence or absence of specific traits.

3. **Definition of Statements in the Key**: Each statement in the key represents a choice between two contrasting options. These statements guide the user towards identifying the organism correctly.

4. **Terminology**: The specific term used to refer to each statement in the key is "lead." A lead provides the necessary information to help differentiate between two options.

5. **Conclusion**: Therefore, the answer to the question is that each statement in the key is called a "lead."

### Final Answer:
Each statement in the key is called a **lead**.