Answer:
a) true
Step-by-step explanation:
One of the important factors behind the formation of clouds is the stability of the atmosphere. Air gets condensed with the increase in the height, while it becomes warm with a decrease in its height. A stable air is the type of air that can sink. The air which has low temperature has more density than the air it is surrounded by. When clouds are formed with stable air, the clouds formed are thin and horizontal.