[单选题]
An object sits on a frictionless surface. A 13:b5;jb ag)aop ttyc zoq(b:56-N force is ap)9ol mmuxf 2f6uqk(7)q ka *jnplied to the object,k*))m9m 62folk(xjuuq 7 afq n and it accelerates at $2.0 \; m/s^2$. What is the mass of the object?
A. $4.0 \; kg$
B. $8.0 \; kg$
C. $32 \; kg$
D. $78 \; N$
