{\obeylines%
WY5V8181
HR
}
\noindent(a)

Speed is absolute velocity (i.e. regardless of direction). Both A and B
have increasing absolute distance from the x-axis at every time shown on
the graph, so neither has decreasing speed.

\noindent(b)

At $t=0$, $t=2$, A and B are moving at the same speed because their
lines on the graph intersect.

\noindent(c)

Object A.

\noindent(d)

$$W = \Delta E.$$
The initial velocities of both objects are zero, so their initial
energies are zero, and $$W = E_f = {1\over2}mv^2.$$ Because
$m_A = m_B,$ and $$|v_A| > |v_B| \to v_A^2 > v_B^2\hbox{ at $t=4$},$$
object A has more energy and has thus had more net work done to it.

\bye