Using the given $\mathrm{v}-\mathrm{t}$ graph, one can conclude:

A: Displacement in ($0-4$) seconds is equal to the displacement in ($4-6$) seconds.
B: Acceleration is $2.5 \mathrm{m} {\mathrm{s}}^{-2}$ in $\mathrm{OA}$ and zero in $\mathrm{AB}$.
C: Acceleration is negative in time ($6-8$) seconds.