A couple has six daughters. What is the possibility of their having a girl next time ?

Options

A. `10 %`
B. `50 %`
C. `90 %`
D. `100 %`

Explanation

To solve the question regarding the possibility of a couple having a girl after already having six daughters, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Genetic Basis**: In humans, sex is determined by the combination of sex chromosomes. Males have one X and one Y chromosome (XY), while females have two X chromosomes (XX).

2. **Gamete Formation**: During reproduction, males produce two types of gametes: one carrying the X chromosome and the other carrying the Y chromosome. Females produce only one type of gamete, which carries the X chromosome.

3. **Fertilization Outcomes**: When a male gamete (X or Y) fertilizes a female gamete (X), the possible combinations are:
- X (from female) + Y (from male) = XY (male offspring)
- X (from female) + X (from female) = XX (female offspring)

4. **Ratio of Offspring**: The probability of having a male or female offspring is equal. Therefore, the ratio of male to female offspring is 1:1.

5. **Calculate Probability**: This means that the probability of having a girl (female) or a boy (male) is 50% for each birth, regardless of the sex of previous children.

6. **Conclusion**: Therefore, the possibility of the couple having a girl next time is 50%.

### Final Answer:
The possibility of the couple having a girl next time is **50%**.

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