What purpose do sentences 3 through 6 serve in this paragraph?

(1) My family has a quaint cottage at a small, private lake. (2) The cottage is about 75 years old, but we try to keep it in good condition. (3) The outside is white with green trim on the windows and shutters. (4) In front of the cottage is a flagstone walk that leads down to a stone patio. (5) The patio itself is right next to the water. (6) Out from the patio stretches a dock where we keep a small rowboat tied. (7) Every summer, my family sets aside a week when we all get together at the lake for a family vacation/reunion.

A. They set up a comparison.
B. They show cause and effect.
C. They provide supporting details.
D. They introduce the main idea.

The correct answer is the following: option c. From sentence 3 to sentence 6 the author of the paragraph is providing supporting details. These sentences give the audience a in detailed description of how the family's cottage is like how old it is, the physical appearance of its exterior and its surroundings. The purpose of including all of these supporting details is to create a vivid image of the cottage on the reader's mind so that this last one can have a sense of being a part of the story he/she is reading.