Which of the following statements is incorrect ?

Options

A. Earthworms and leeches are hermaphrodite animals.
B. Young ones of animals showing external fertilisation receive little or no parental care.
C. If the egg is not fertilised, it is thrown out of the body along with the lining of the uterus as menstrual flow.
D. Sex organs in human beings are formed at puberty.

Explanation

**Step-by-Step Solution:**

1. **Identify the Statements:** The question presents four statements regarding reproduction in organisms. We need to determine which one is incorrect.

2. **Evaluate Statement 1:** "Earthworms and leeches are hermaphrodite animals."
- **Analysis:** This statement is correct. Hermaphrodites possess both male and female reproductive organs. Earthworms and leeches are indeed classified as hermaphrodites.

3. **Evaluate Statement 2:** "Young ones of animals showing external fertilization receive little or no parental care."
- **Analysis:** This statement is also correct. Animals that undergo external fertilization, such as many fish and amphibians, typically provide minimal to no parental care for their offspring.

4. **Evaluate Statement 3:** "If the egg is not fertilized, it is thrown out of the body along with the lining of the uterus as menstrual flow."
- **Analysis:** This statement is correct. In human females, if an egg is not fertilized, it is expelled from the body during menstruation, along with the uterine lining.

5. **Evaluate Statement 4:** "The sex organs in humans are formed at puberty."
- **Analysis:** This statement is incorrect. The primary sex organs in humans develop during embryonic development, long before puberty. Puberty is the stage when these organs mature and become functional.

6. **Conclusion:** Based on the evaluations, the incorrect statement is the fourth one: "The sex organs in humans are formed at puberty."

**Final Answer:** The incorrect statement is option 4.

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