Question

Can anyone help me please?

Answer 1

The answer is C because they are all adding 4 to get to the next number

Answer 2

An arithmetic sequence is a sequence of numbers where the difference between each of the consecutive terms (aka terms following each other) remains the same. 

You can answer your question by taking each choice and finding the difference between the consecutive values. If that difference remains constant, then the sequence if arithmetic.

For A, 12-9 = 3, but 16-12 = 4, so it's not arithmetic.
For B, 11-9 = 2, but 16-13 = 3, so it's not arithmetic.
For D, (1/4)-(1/2) = -1/2, but (1/6)-(1/4) = -1/12, so it's not arithmetic.

That means C is an arithmetic sequence. And if you look at the difference between all consecutive terms, the difference is a constant 4.