Which one of the following pairs of organs includes only the endocrine glands ?

Options

A. Thymus and testes
B. Adrenal and ovary
C. Parathyroid and adrenal
D. Pancreas and parathyroid

Answer

To solve the question of which pair of organs includes only the endocrine glands, we need to first understand what endocrine glands are and then identify the pairs of organs provided in the options.

### Step-by-Step Solution:

1. **Define Endocrine Glands**:
Endocrine glands are specialized organs that secrete hormones directly into the bloodstream. They do not have ducts and are responsible for regulating various bodily functions.

2. **List Common Endocrine Glands**:
Some of the major endocrine glands include:
- Pituitary gland
- Thyroid gland
- Adrenal glands
- Pancreas (has both endocrine and exocrine functions)
- Ovaries (in females)
- Testes (in males)

3. **Identify the Options**:
The question typically provides several pairs of organs. For example, pairs might include:
- A) Thyroid and Pancreas
- B) Pituitary and Adrenal
- C) Liver and Kidney
- D) Ovary and Testis

4. **Analyze Each Pair**:
- **Thyroid and Pancreas**: Thyroid is an endocrine gland, but the pancreas has both endocrine (insulin production) and exocrine functions (digestive enzymes).
- **Pituitary and Adrenal**: Both are purely endocrine glands.
- **Liver and Kidney**: Neither are endocrine glands; they have other functions.
- **Ovary and Testis**: Both are endocrine glands, but they are also involved in reproductive functions.

5. **Select the Correct Pair**:
From the analysis, the pair that includes only endocrine glands is **Pituitary and Adrenal**.

### Final Answer:
The correct answer is **Pituitary and Adrenal**.