Explanation:

- Let's analyze the pattern in the series: 7, 8, 15, 18, 23, 28, 31, 38, ?

- The differences between consecutive numbers are: 1, 7, 3, 5, 5, 3, 7.

- It appears the differences alternate in a pattern: 1, 7, 3, 5, and then repeat.

- To find the next difference after 38, we need to determine the next number in the sequence of differences. Thus, after 7, the series repeats with 1.

- Therefore, the next number should be 38 + 1 = 39.

- Comparing with options, Option:1 is correct: 39

Correct Answer: 39

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