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Best answer

We use Euler's formula for planar graphs : $v-e+f=2$ where,

- $v\;-$ no. of vertices,
- $e\;-$ no.of edges and
- $f\;-$ no. of faces. (Refer: Euler's Formula)

So, $25-e+17=2$ $\Rightarrow$ $e=40$

Option C is correct.