Final answer:
The given sequence 11, 22, 33, 44, 55, ... is an arithmetic sequence with a common difference of 11.
Step-by-step explanation:
The given sequence 11, 22, 33, 44, 55, ... is an arithmetic sequence.
In an arithmetic sequence, the difference between consecutive terms is constant. In this sequence, the difference between each term is 11, so it is an arithmetic sequence.
To find the common difference, we subtract any two consecutive terms:
22 - 11 = 11, 33 - 22 = 11, 44 - 33 = 11, and so on.
Therefore, the correct answer is a) Arithmetic.