The correct answer is option 'A': Ninety gallons of water.

Explanation:
Camels are well known for their ability to survive in arid desert conditions, where water is scarce. They have developed remarkable adaptations that allow them to conserve water and withstand long periods without drinking. When they do have access to water, camels can consume a large amount to replenish their reserves.

Here is a detailed explanation of why the correct answer is option 'A':

Camels and Water Consumption

- Camels are able to drink a significant amount of water when it is available. They have a remarkable capacity to store water in their bodies, allowing them to survive in harsh desert environments.
- A thirsty camel can consume up to 30% of its body weight in water at one time. This means that a camel weighing around 300 pounds (136 kilograms) can drink up to 90 gallons (340 liters) of water.
- The ability to consume such a large amount of water helps camels to survive in the desert, where they may not have access to water for several days or even weeks.

Water Storage in Camels

- Camels have several adaptations that allow them to store and conserve water effectively. One of these adaptations is their hump, which is not actually filled with water but with fat.
- The fat in the hump serves as an energy reserve that camels can draw upon when food and water are scarce. As the fat is metabolized, it releases water for the camel to use.
- Additionally, camels have efficient kidneys that enable them to reabsorb water from their urine, reducing water loss.

Surviving in the Desert

- The ability to drink a large amount of water and store it within their bodies allows camels to survive in the harsh desert environment.
- While other animals would quickly become dehydrated in such conditions, camels can withstand long periods without drinking and still maintain their bodily functions.
- They can conserve water by minimizing sweating, reducing urine production, and even adjusting their body temperature to reduce water loss through respiration.

In conclusion, a thirsty camel can drink as much as ninety gallons of water to replenish its water reserves. This ability, along with other adaptations, allows camels to survive in arid desert environments where water is scarce.