9th grade math.

This is a geometric sequence and the common ratio is equal to 1/3

Explanation:

The sequence is not arithmetic because the gap between 45 and 15 is not the same as the gap from 15 to 5

Note how

Showing that we dropped by 30 when going from 45 to 15, but then we dropped by 10 when going from 15 to 5.

This gap or jump must be the same to have an arithmetic sequence.

This sequence is geometric though.

We can see that by dividing each term by its previous term

Each time we get the same result 1/3 after reducing. If we didn't get the same result each time, then this sequence wouldn't be geometric.

But since we do get the same result each time, this tells us that the common ratio is 1/3. Each new term is 1/3 that of the previous term

For instance,

term2 = (1/3)*term1 = (1/3)*45 = 15

i believe the answer is d.

hope it you! : d