The answer to that are c and b or b and c I hope that this helps!
We are given the first term and the common ratio, this means they belong to a geometric series.
For the given series:

Each term of the geometric series is obtained by multiplying the previous term by common ratio.
So the next terms will be:
-4.5, -6.75, -10.125, -15.1875, -22.78125
The general formula for the G.P would be:

On plotting the series, the result will be like this:
Answer will be C y=-x+6
Why?
The line or scatterpoints are going down from left to right which means it is a negative slope
As you can see one point is at 1,5 and the other is at 0,6 which means the slope goes down by 1
Giving you -x
What is the y intercept?? It is 6 so that completes the line equation
Y=-x+6 hope that helps