In what way does the author build suspense in the story?

A.

by contrasting Clara's voice with that of the stranger

B.

by describing a windy evening

C.

by describing the clothing of the stranger

D.

by describing the nervous anticipation of Clara and her sisters

The Windy Evening

Clara and her sisters May and Kiara had come to Ohio to visit their grandparents. After spending the day baking cookies with their grandmother, the three sisters were sitting by the fireplace and teaching their grandpa how to use his new cell phone.
Suddenly, they heard the windows rattle. A strong wind was blowing and Clara rushed to shut the windows. She was tempted to peek out of the window for a moment. There, in the dim light, she saw a tall figure in a long coat and a hat walking past the gate, but a second later, she saw the figure move toward their house. Clara gestured to her sisters to come to the window and pointed at the person approaching. Their hearts skipped a beat when they heard a knock on the door.
"Who could it be at this hour?" they wondered, before saying it aloud.