Take the factors considered by earned value analysis and subtract those considered by tracking Gantt charts. The factor(s) you have remaining are: a. Cost and schedule.
b. Performance.
c. Schedule and performance.
d. Cost.

cost

Explanation:

In earned value analysis also referred to as the gold triangle method, the cost, performance and time are considered. A tracking Gantt chart shows the stage of completion for every task. It allows individuals or project team make comparison between two sets of dates in order to track the progress of an acctivity against the original plan. Therefore, the tracking Gantt chart comsiders the performance and time.

Therefore cost is the only factor remaining