A particle is moving straight at constant acceleration. The particle positions change depending on the time following equation r(t)=α+βt-γt^2 with r in meter and t in seconds. The units of α,β, and γ are …… respectively
a. m, m, m
b. m, m\cdot s, m\cdot s^2
c. m, m\cdot s^{-1}, m\cdot s^{-2}
d. m\cdot s^2, m\cdot s, m
e. m\cdot s^{-2}, m\cdot s^{-1}, m