The correct answer is (a).
The series is a list of numbers that are the product of the first $n$ prime numbers, where $n$ is the position of the number in the series. For example, the first number in the series, 6, is the product of the first two prime numbers, 2 and 3. The second number in the series, 10, is the product of the first three prime numbers, 2, 3, and 5. The third number in the series, 27, is the product of the first four prime numbers, 2, 3, 5, and 7.
Following this pattern, the sixth number in the series should be the product of the first six prime numbers, 2, 3, 5, 7, 11, and 13. This product is 3003, which is not equal to 3084. Therefore, 3084 is the wrong term in the series.
The other options are all correct terms in the series. 10 is the product of the first two prime numbers, 2 and 3. 27 is the product of the first four prime numbers, 2, 3, 5, and 7. 104 is the product of the first five prime numbers, 2, 3, 5, 7, and 11. 505 is the product of the first six prime numbers, 2, 3, 5, 7, 11, and 13. 21581 is the product of the first seven prime numbers, 2, 3, 5, 7, 11, 13, and 17.