Find the derivative of the velocity-time graph with respect to time (t). The instantaneous acceleration (a) is the rate of change of velocity with respect to time.

Given the velocity-time graph: v = 2t + 4 (where v is in m/s and t is in seconds)

1. Find the acceleration by taking the derivative of velocity with respect to time:
a = dv/dt
a = d/dt (2t + 4)
a = 2 (since the derivative of 4 with respect to t is 0)

So, the instantaneous acceleration of the particle is constant and equal to 2 m/s² for all values of time (t).

Therefore, the answer is the same for all options (a), (b), (c), and (d). The instantaneous acceleration of the particle at any time is 2 m/s^2.