When is a project ahead of schedule?

The Correct answer is B. SPI>1

CPI and SP are a measure of performance. 1 means it is on budget and less than 1 means it is underperforming per unit of cost or time. My thinking is to be ahead of schedule is that performance is better than 1 therefor B or C. 

Assuming that B is SPI, both B & C does show that project is ahead of schedule. But C also shows that Cost performance is good.

First, let me explain CPI and SPI

• Cost Performance Index (CPI): Represents the amount of work being completed on a project for every unit of cost spent. CPI is computed by Earned Value / Actual Cost. A value of above1 means that the project is doing well against the budget.
• Schedule Performance Index (SPI): Represents how close actual work is being completed compared to the schedule. SPI is computed by Earned Value / Planned Value. A value of above one means that the project is doing well against the schedule.

Thus, the question is when is project ahead of shedule, thus answer is B. SPI >1

But C. SPI & CPI >1 indicates schedule is ahead with good cost.

Option B = SPI > 1

thats when the earned value is more than the planned value..

Schedule performance index i,e SP is more then 1