**Explanation:**

The correct answer is option 'A', which comprises the animals cow, goat, rabbit, and deer. These animals are all herbivorous, meaning they primarily feed on plants. Let's analyze each option to understand why option 'A' is the correct answer.

**Option A: Cow, Goat, Rabbit, Deer**
- **Cow:** Cows are herbivorous animals that mainly consume grass and other plant material.
- **Goat:** Goats are also herbivores and feed on a variety of plants, including grass and leaves.
- **Rabbit:** Rabbits are known for their herbivorous diet, consisting of grass, leaves, and other plant material.
- **Deer:** Deer are herbivores that graze on grass, leaves, and other vegetation.

All the animals in option 'A' are herbivorous, making it the correct answer.

**Option B: Cow, Goat, Rabbit, Wolf**
- **Cow, Goat, Rabbit:** These animals are herbivorous, as discussed above.
- **Wolf:** Wolves, on the other hand, are carnivorous animals that primarily feed on meat. They are not herbivores.

Since the option includes a carnivorous animal (wolf), it cannot be the correct answer.

**Option C: Wolf, Goat, Rabbit, Deer**
- **Wolf:** Wolves are carnivorous animals and do not feed on plants.
- **Goat, Rabbit, Deer:** These animals are herbivorous, as discussed above.

Since the option includes a carnivorous animal (wolf), it cannot be the correct answer.

**Option D: Cow, Crow, Crane, Camel**
- **Cow:** Cows are herbivorous animals, as discussed above.
- **Crow, Crane:** Crows and cranes are omnivorous birds that have a varied diet including insects, fruits, seeds, and carrion. While they may consume plant material, they are not strictly herbivorous.
- **Camel:** Camels are herbivorous animals that primarily feed on desert vegetation.

Although the option includes some herbivorous animals (cow and camel), it also includes omnivorous birds (crow and crane). Therefore, it cannot be the correct answer.

In conclusion, option 'A' is the correct answer as it comprises only herbivorous animals: cow, goat, rabbit, and deer.