Explanation:

Since Pooja and Shipra are twins so their ages be same.

Let their ages be x and age of Mounika be y , then 

x+x = y    -------(1) 

 and   x−3 /y−3 = 2/7

⇒7x−2y = 15

Now, from  equation (1), 

7x - 4x = 15  =>  x = 5

So the age of Shipra 3 years hence will be 5+3 = 8 years

Hence, option 3 is the correct answer.