The correct answer is: B. Shimla
Shimla is a hill station in Himachal Pradesh, India. It is the capital of the state and is also a popular tourist destination. The city is located in the foothills of the Himalayas and has a pleasant climate. Shimla is also home to a number of historical buildings, including the Viceregal Lodge, which was the summer capital of British India.
The Indian Air Force (IAF) has a base in Shimla, which is known as the Shimla Air Force Station. The base is located at the outskirts of the city and is used for training and operational purposes. The IAF base in Shimla is one of the oldest in the country and has played a significant role in the history of the IAF.
The other options are incorrect because they are not hill stations in Himachal Pradesh that also serve as air force bases. Kasauli is a hill station in Himachal Pradesh, but it does not have an air force base. Manali is a town in Himachal Pradesh, but it is not a hill station. Khajjiyar is a village in Himachal Pradesh, and it does not have an air force base.