ANSWER is "an early".In the given sentence, the word 'riser' means a person who habitually gets out of bed at a particular time of the morning.Let us explore the given OPTIONS:Fast will act as an ADJECTIVE means moving or capable of moving at HIGH speed.Early will act as an adjective means happening or DONE before the usual or expected time.Easy will act as an adjective means achieved without great effort; presenting a few difficulties.Steady will act as an adjective means not changing; regular and established.Hence, the correct answer is option 2. Complete Sentence: My mother is an early riser.