3. Which of the following illustrates an arithmetic sequence? A. 1, 1, 2, 3, 5, ... B. 1, 4, 9, 16, 25, ... C. 1, 2, 4, 8, 16, ... D. 1, 2, 3, 4, 5, .. 4. If the first term of an arithmetic sequence is - 15 and the 5th term is 13, what is common difference? A. 7 B.6 C.5 D. 4