The Brookville BL12CG is a 4-axle diesel-electric locomotive built by the Brookville Equipment Corporation. The locomotive is designed to meet Tier 4 emissions standards. The first two were delivered to the Central California Traction Company in April 2015.
The Central California Traction Company bought two locomotives in 2015.
We know from the context that the Central California Traction Company obtained at least two locomotives in the year 2015. We don't know whether or not they were purchased. Even if they were definitely purchased, we don't know if they purchased more than two in the year 2015. I think that the system had an issue with this question because it didn't consider the fact that the company may have purchased more locomotives later in the year.