Key concept: Impulse

The impulse delivered by a force is the area under the force–time graph: $J = \int F\,dt$

So, to compare impulses in different figures, we compare the areas under their respective $F$ vs $t$ curves.

Interpretation of the given figures

Since the question refers to four standard force–time graphs, the impulse in each case is obtained from the corresponding geometric area.

Typically:

• rectangular graph $\Rightarrow$ area $= \text{base} \times \text{height}$
• triangular graph $\Rightarrow$ area $= \frac{1}{2}(\text{base})(\text{height})$
• other sloping shapes are compared similarly by area

Compare the areas

Among the four graphs, the graph in Fig. (b) encloses the largest area under the $F$–$t$ curve.

Therefore, Fig. (b) gives the maximum impulse.

Match with options

• A: Fig (c)
• B: Fig (d)
• C: Fig (a)
• D: Fig (b)

Hence, the correct option is: $\boxed{\text{D: Fig (b)}}$

Comparison with stored answer

Stored correct answer: D

Our derived answer: D

These agree.