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 number in a certain taxon of insects, we need to analyze the information provided step by step.

### Step-by-Step Solution:

1. **Understanding Chromosome Numbers**:
- We are given two groups of insects: one group has 17 chromosomes, and the other has 18 chromosomes.

2. **Identifying the Sex Determination System**:
- In insects, the sex determination system can be of the XO/XX type. In this system, males typically have one sex chromosome (X) and a set of autosomes, while females have two sex chromosomes (XX) along with their autosomes.

3. **Assigning Chromosome Counts**:
- For the males in this insect taxon, the chromosome count can be represented as:
- Males: 16 autosomes + 1 X chromosome = 17 total chromosomes.
- For the females, the chromosome count can be represented as:
- Females: 16 autosomes + 2 X chromosomes = 18 total chromosomes.

4. **Conclusion**:
- From our analysis, we can conclude that the insects with 17 chromosomes are males (having XO configuration), and the insects with 18 chromosomes are females (having XX configuration).

5. **Final Answer**:
- Therefore, the correct answer is that the 17 chromosome-bearing organisms are males and the 18 chromosome-bearing organisms are females.