Initially, Rupa is 9th from the left and Shikha is 10th from the right.
After interchanging their positions, Rupa becomes 16th from the left.
Since Rupa is now in Shikha's original position, Shikha's original position was 16th from the left.
We also know that Shikha is 10th from the right.
For any position in a row:
Total number of girls = Position from left + Position from right − 1
Using Shikha's position:
Total =16+10−1
Total =25
Therefore, there are 25 girls in the row.
The answer is Option 3: 25.