**Bats** are the only aerial animals that give birth to their young ones. Let's explore why this is the correct answer.

**Explanation:**

**1. Introduction:**
- Aerial animals are those that are adapted to live and move in the air.
- Some examples of aerial animals include birds, bats, insects, and flying squirrels.

**2. Birth in Aerial Animals:**
- Most aerial animals, including birds, lay eggs to reproduce.
- They build nests, lay their eggs in them, and incubate the eggs until they hatch.
- The young ones then emerge from the eggs as fully-formed hatchlings.

**3. Bats - Unique Aerial Animals:**
- Bats, on the other hand, are unique aerial animals because they give birth to live young ones instead of laying eggs.
- They are the only mammals that are truly capable of sustained flight.
- Bats have adapted to their aerial lifestyle by developing specialized wings and a lightweight body structure.

**4. Reproduction in Bats:**
- Female bats have a reproductive system similar to other mammals.
- They have a uterus where the fertilized eggs develop.
- The fertilization occurs internally, with the male bat transferring sperm to the female bat during mating.
- The embryos develop inside the female bat's body, receiving nourishment through a placenta-like structure.

**5. Birth of Young Ones:**
- After a gestation period, which varies depending on the species, the female bat will give birth to live young ones.
- The newborn bats, called pups, are usually born headfirst and are relatively well-developed.
- The mother bat typically catches the pup in her wings and cleans it using her mouth.
- Once the pup is clean and dry, it clings to its mother's body or hangs from a nearby surface.

**6. Maternal Care:**
- Bats exhibit strong maternal care, with the mother bats providing milk and protection to their young ones.
- The pups nurse from their mother's nipples and grow rapidly in the early weeks of their lives.
- As they grow, the mother bat may leave the pup in a safe location, such as a roost, while she goes out to forage for food.
- Once the pup is old enough and capable of flight, it will accompany the mother bat on hunting trips.

In conclusion, out of the given options, bats are the only aerial animals that give birth to their young ones. They are unique among aerial animals because they are mammals that have adapted to sustained flight. The mother bats provide care and nourishment to their live-born pups until they are capable of independent flight.