Which of the following is written in correct scientific notation?

a. 809 * 104

b. 80.9 * 104

c. 80.9 * 10-4

d. 8.09 * 104

first, correct answer gets brainiest

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How many different three-digit numbers can be formed using the digits 1 comma 2 comma 9 comma 6 comma 4 comma 3 comma and 8 without repetition? for example, 664 is not allowed.

Mrs. gehrke said cheddar weighs 16.8 pounds. he actually weighs 15.2 pounds. what is the percent error?