Forms when a cooler air mass displaces a warmer air mass and usually indicates drops in temperature, heavy rains, and sometimes hail, thunder, or lightning.

Cold Front

Explanation: When cooler air mass pushes warm air mass it rise into the atmosphere since it is less dense forming clouds. During a cold front there is a relative decrease in the air temperature where the cooler air mass moved.

well for one plants are always the producer, so a is the answer. a wolf is more of the consumer(predator) and the deer is the prey so i know those two are out of the question. also mushrooms are fungi/fungus so a is the producer.