Which is one factor that will affect the type of cloud that will form? -altitude. -wind direction. - color of clouds. - size of pellets

altitude.

Explanation:

As air rises in the atmosphere, it becomes cool because air pressure is less at that altitude. So, when the air cools to a certain degree, it is unable to hold the water vapor and this vapor becomes water droplets and thus, cloud is formed.

Other factors also influence cloud formation such as topography, humidity, etc but according to the question and with regards to the options available, the correct answer is altitude.

altitude

Explanation:

Altitude is responsible for the formation of different types of clouds. There are three types of clouds on the basis of altitude i. e. low level clouds such as cumulus, stratus etc which are present at the height below  6,500 feet, the middle level clouds such as altocumulus and nimbostratus etc which are present between 6,500 and 20,000 feet and high level clouds such as cirrus, cirrocumulus etc that is present above 20,000 feet.

d is the logical answer but im not a 100% sure