b
From graph it is clear that wher 

\(\mathrm{L}=1 \mathrm{m}, \mathrm{T}^{2}=4 \mathrm{s}^{2}\)

As we know,

\(\mathrm{T}=2 \pi \sqrt{\frac{\mathrm{L}}{\mathrm{g}}}\)

\(\Rightarrow \mathrm{g}=\frac{4 \pi^{2} \mathrm{L}}{\mathrm{T}^{2}}\)

\(=4 \times\left(\frac{22}{7}\right)^{2} \times \frac{1}{4}=\left(\frac{22}{7}\right)^{2}\)

\(\therefore \mathrm{g}=\frac{484}{49}=9.87 \mathrm{m} / \mathrm{s}^{2}\)