Which One of the Following Is the Best Example of Someone

Which one of the following is the best example of someone using a heuristic rather than an algorithm) in problem solving?

A) Susan wants to know how long it will take her to drive from Phoenix to Los Angeles. She knows that the distance is 400 miles, and she figures she will average 50 miles an hour with stops, so she predicts the trip will take 8 hours.
B) Vinnie has a round hot tub that is six feet in diameter; he wants to build a top to cover it. He remembers the formula for calculating the area of a circle and works out how many feet of lumber he needs.
C) John wants to buy a computer. He compares prices at different computer stores and buys whichever model is least expensive.
D) Marion can't think of a plot for the short story she needs to write. She breaks her task into smaller pieces: First she'll decide who the main character will be, then she'll think of a conflict for that character to experience, and finally she'll identify a reasonable resolution of that conflict.