Question

by which chromosomes boy will be born

Answer 1

$\textbf{\large{Answer -}}$

The male chromosomes are $\textbf{(XY)}$ .

While the female chromosomes are $\textbf{(XX)}$ .

When the fertilisation takes place either of the two unites and forms a zygote.

For a baby boy, the chromosome responsible are (XY)

And for baby girl, the chromosome responsible are (XX)

Answer 2

Here is your answer.

XY chromosomes is your answer.

Hope that this helps you.