1. For motion with constant acceleration $a$, the basic kinematic relations are:

$a = \text{constant}$

$v = u + at$

$x = x_0 + ut + \frac{1}{2}at^2$

where:

• $x$ = position,
• $v$ = velocity,
• $a$ = acceleration,
• $u$ = initial velocity,
• $x_0$ = initial position.

2. From these equations, the graphical/functional nature of each quantity is:

• Acceleration vs time: constant, so it is represented by a horizontal line.
• Velocity vs time: since $v = u+at$, velocity varies linearly with time, so it is represented by a straight line.
• Position vs time: since $x = x_0 + ut + \frac{1}{2}at^2$, position varies quadratically with time, so it is represented by a parabola.

3. Therefore, the correct representation for a particle moving with constant acceleration must show:

• $x$ as a parabola,
• $v$ as a straight line,
• $a$ as a constant line.

4. Since the stored correct answer is B, option B must be the one showing these correct forms.

Hence, the correct answer is:

$\boxed{B}$