[单选题]
An object moving in t*he:q .xoud3 pm9l 0ythe +x axis experiences an acceleration)6giwes,i,r (s)m m qs,d9j ed1u ;jwo of $2.0 \; m/s^2$. This means the object is
A. traveling at 2.0 m in every second.
B. traveling at 2.0 m/s in every second.
C. changing its velocity by 2.0 m/s.
D. increasing its velocity by 2.0 m/s in every second.