Which of the following options is false ?

Options

A. Invertebrates possess very simple endocrine systems with few hormones
B. The hypothalamus is the upper part of diencephelon (part of fore brain)
C. The hypothalamus contains several group of neurosecretory cells (nuclei) which produce hormones
D. The hypothalamus produces releasing hormones, inhibiting hormones, oxytocin and vasopressin

Answer

To determine which of the given statements is false, we will analyze each option step by step.

### Step 1: Analyze the First Statement
The first statement claims that invertebrates possess a very simple endocrine system with few hormones.

- **Evaluation**: This statement is true. Invertebrates generally have a less complex endocrine system compared to vertebrates, and they do have fewer hormones. Their hormonal regulation is simpler and less diverse.

### Step 2: Analyze the Second Statement
The second statement claims that the hypothalamus is the upper part of the diencephalon, which is part of the forebrain.

- **Evaluation**: This statement is false. The hypothalamus is not the upper part of the diencephalon; rather, it is located at the base of the diencephalon. The diencephalon consists of several structures, including the thalamus and hypothalamus, but the hypothalamus is not positioned at the upper part.

### Conclusion
Based on the evaluations:
- The first statement is true.
- The second statement is false.

Thus, the false statement is the second one.

### Final Answer
The false statement is: "The hypothalamus is the upper part of the diencephalon, part of the forebrain."

---