I actually got this right but in thinking about I don't see why B isn't correct. How could 2 be possible if zero wasn't in the middle? If T were the same distance then either R would equal -S, in which case 0 would have to be in the middle, or S would initially be negative and the opposite would have to equal the sum of T and -R, which would make S initially to left of R and not possible according to the parameters. For example, if R were -2 and T were 4, S would either have to equal 2 or -6, and it couldn't be -6 because that would put it to the left of the R on the number line.

Could someone provide an example?

I posted an explanation to a very similar problem here:

https://www.beatthegmat.com/best-approac ... 67985.html