The number of ways in which 3 boys and 2 girls can be arranged in a queue, given that the 2 girls have to be next to each other, is

12
24
48
120

The correct answer is (c) 48.

We can think of the 5 people as 2 groups: the 2 girls and the 3 boys. The 2 girls can be arranged in 2! ways, and the 3 boys can be arranged in 3! ways. So the total number of ways to arrange the 5 people is $2!3! = 48$.

Here is another way to think about it. Imagine that the 2 girls are always together, like a single unit. Then we have 4 people to arrange, and there are $4!$ ways to do this. But the 2 girls can be arranged within their group in 2! ways, so we have to multiply $4!$ by 2! to get the total number of arrangements: $4!2! = 48$.

Option (a) is incorrect because it is the number of ways to arrange 5 people without any restrictions. Option (b) is incorrect because it is the number of ways to arrange 3 boys and 2 girls if the girls must be in different positions. Option (d) is incorrect because it is the number of ways to arrange 3 boys and 2 girls if the girls must be in the same position.