Over the Past Several Decades, the Overall Trend for Earth's

Over the past several decades, the overall trend for earth's temperatures has been

A) increases in overall global temperatures at an accelerating rate, a phenomenon known as global warming.
B) cyclical periods of warming and cooling, known as global climate change.
C) a gentle trend towards colder winters and hotter summers, which averages out to be very little overall global temperature changes.
D) decreases in overall global temperatures at an accelerating rate, a phenomenon known as global cooling.