The correct answers are option A, It must be 1,000 miles or more in size.option C, It flows as one unit and option E, It has a uniform temperature and humidity.
An air mass is an extremely large patch of air which flows as a single entity. The temperature and humidity conditions within an air mass are same. The physical characteristics of air mass are acquired from the region of its source. However, a flowing air mass imparts its properties to the region where is stays or sits over for several days. These are pushed by high level winds. The prevalent size of an air mass is 1600 km (1000 miles) or more.