Hi Guy Martin
As the 4 possible answers are expressed in %, my understanding is the answers are related to CPI and SPI, not to CV and SV
A CPI value greater than 1.0 indicates a cost underrun of performance to date. You are right.
But using your numbers, CPI will be 1.111 (11%) instead of 1.1 (10%)
CPI = EV/AC = 5000/4500 = 1,1111
There are no possible answers with 11%
This is why, we have to calculate the SPI and to use the PV
SPI=EV/PV

The cost baseline is the cost of the project. It will include all the costs of all the deliverables on the project. The cost baseline is what will be included in the project management plan and will be used to measure the performance of the project once it is executed. This is alsoknown as the budget at completion (BAC). A.R book so
BAC= The cost baseline= cost estimates+ contingency reserves=9,500+0,500=10,000.
EV=50%*BAC=5,000
AC=4,500
CV=5000-4500=500 so the projet is cost 500 lower than 5000 (10% lower)
Don't use PV (this is misinformation) . Costs are always compared to the earned value.

The correct answer will be C
AC = $4500
CPI = EV/AC = 4750/4500= 1,05
The project cost is 5% higher than planned.

The correct answer will be C
EV = $9500*50%=$4750
PV = $9500*40%=$3600
SPI = ($4750/$3600)=1.25, so actual work is more than 25% of the planned work