Consider the following hormones
(i) Antidiuretic hormone
(ii) Aldosterone
(iii) Parathormone (iv) Oxytocin
In the vertebrate animals, the hormones involved in the control of osmoregulation would include

Options

A. (i), (ii), (iii) and (iv)
B. (i), (ii) and (iii)
C. (i) and (ii)
D. (iii) and (iv)

Answer

To determine which hormones are involved in the control of osmoregulation in vertebrate animals, we will analyze each hormone mentioned in the question.

### Step-by-Step Solution:

1. **Identify the hormones:**
- Antidiuretic hormone (ADH)
- Aldosterone
- Parathormone
- Oxytocin

2. **Analyze Antidiuretic Hormone (ADH):**
- ADH is responsible for regulating water balance in the body by controlling the amount of water reabsorbed by the kidneys. It plays a crucial role in osmoregulation.
- **Conclusion:** ADH is involved in osmoregulation.

3. **Analyze Aldosterone:**
- Aldosterone is known as the "salt-retaining hormone." It helps maintain water and electrolyte balance by promoting sodium reabsorption in the kidneys, which indirectly affects water retention.
- **Conclusion:** Aldosterone is also involved in osmoregulation.

4. **Analyze Parathormone:**
- Parathormone (or parathyroid hormone) regulates calcium levels in the blood and has no direct role in water balance or osmoregulation.
- **Conclusion:** Parathormone is NOT involved in osmoregulation.

5. **Analyze Oxytocin:**
- Oxytocin is primarily involved in reproductive functions, such as stimulating uterine contractions during labor. It does not play a role in osmoregulation.
- **Conclusion:** Oxytocin is NOT involved in osmoregulation.

6. **Final Assessment:**
- The hormones involved in osmoregulation are ADH and Aldosterone.
- Therefore, the correct answer is option C: "first and second" (ADH and Aldosterone).

### Final Answer:
**C: First and Second (Antidiuretic hormone and Aldosterone)**

---