In a certain taxon of insects some have 17 chromosomes and the others have 18 chromosomes. The 17 and 18 chromosome-bearing organisms are

Options

A. males and females, respectively
B. females and males,respectively
C. all males
D. all females

Explanation

To solve the question regarding the chromosome numbers in a certain taxon of insects, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Chromosome Count**: We are given that some insects have 17 chromosomes while others have 18 chromosomes. This indicates a difference in chromosome composition between two groups within the same taxon.

2. **Identify the Sex Determination System**: In many insects, including certain taxa, sex determination can occur through systems such as XX-XY or XX-XO. In this case, we will consider the XX-XO system, where females are XX and males are XO.

3. **Analyze the Chromosome Composition**:
- **Females (XX)**: In the XX system, females will have two sex chromosomes (X) plus the autosomes. Therefore, if we assume that the total number of chromosomes in females is 18, this suggests they have 16 autosomes and 2 X chromosomes (16 + 2 = 18).
- **Males (XO)**: Males, on the other hand, have one sex chromosome (X) plus the autosomes. If males have 17 chromosomes, this indicates they have 16 autosomes and 1 X chromosome (16 + 1 = 17).

4. **Conclusion**: From the analysis, we can conclude that:
- The organisms with **17 chromosomes** are **males** (XO).
- The organisms with **18 chromosomes** are **females** (XX).

5. **Final Answer**: Therefore, the 17 and 18 chromosome-bearing organisms are males and females, respectively.