There are 4 girls and 6 boys. So in total 10 students.
We are to choose 2 boys and 2 girls. So in total we have to chose 4 students.
Desired Probability = Number of combinations of choosing 2 boys and 2 girls / Total number of combinations.
Total number of combinations will be 10C4 as we are to selected 4 students from 10.
10C4 = 210
Ways to select 2 girls from 4= 4C2 = 6
Ways to select 2 boys from 6 = 15
Number of ways to select 2 boys and 2 girls = 6 x 15 = 90
Thus, the probability of selecting 2 boys and 2 girls will be = 90/210 = 3/7
So, the answer to this question is option B