Answer: The correct option is (D) Arithmetic Series.
Step-by-step explanation: We are given to select the term that best describes the following set of numbers :
6 + 8 + 10 + 12 + ... + (4 + 2n) + ...
Since the terms of the set of numbers are connected by a plus sign, not a comma, so the set of numbers is a series, not a sequence.
This implies that the options (A) and (C) are incorrect.
Now, we see that the two consecutive terms of the series are connected by the following relation :
d = 8 - 6 = 10 - 8 = 12 - 10 = . . . = 2.
That is, two consecutive terms differs by a common difference of 2.
Hence, the given series is an arithmetic one, NOT geometric.
This gives that option (B) is incorrect and option (D) is CORRECT.
Thus, correct option is (D).