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Correct option is B)

**The correct option is B**

**Hint: Consider snells law and Critical angle**

**Critical angle is given as,**

$c=sin_{−1}(μ1 )$

**Where, $μ$ is the refractive index**.

**In order to describe the relation between the angle of incidence and reflection snells law is used.**

$sinrsini =μ$

**Where $i$ is the angle of incidence and $r$ is the angle of reflection.**

**Explanation for correct answer:**

**Step 1: Information required**

Critical angle is given as,

$c=sin_{−1}(μ1 )$

Where, $μ$ is the refractive index.

In order to describe the relation between the angle of incidence and reflection snells law is used.

$sinrsini =μ$

Here, $i$ is angle of incidence

$r$ is the angle of reflection.

Angle of prism $A=75_{o}$

Refractive index $μ=2 $

**Step 2: Calculate the angle of reflection,**

The angle of the prism is the sum of reflection and critical angle.

Then,

$A=r+c$

Substitute the value of critical angle and angle of prism in the above equation

$A=r+sin_{−1}(μ1 )$

$75=r+sin_{−1}(2 1 )$

$75=r+45$

$r=75−45$

$r=45_{o}$

So, the angle of reflection is $r=45_{o}$.

**Step 3: Calculate angle of incidence,**

Consider snells law,

$sinrsini =μ$

$sin30sini =2 $

$sini=2 ×21 $

$sini=2 1 $

$i=sin_{−1}2 1 $

$i=45_{o}$

**Hence the angle of incidence is $i=45_{o}$.**

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