Correct option is A
Given: Mona, Rahul, Vikas, Kavita, Poonam and Khushi, each has a different height.
They are standing in a line according to their heights in an increasing order.
Vikas is taller than only one person.
Only Rahul is standing between Khushi and Vikas.
Mona is shorter than only one person.
Exactly two people are standing between Poonam and Rahul.
From the given information arrangement will be:

So, Kavita is the shortest person in the group.
Thus, Option A is the correct answer.