"I free her from here, but not from there. I have bound her firmly there, so that through the grace of Indra she will have fine sons and be fortunate in her husband's love." From where is this excerpt of a mantra for producing 'fine sons' taken:

Rigveda

The correct answer is Option (4) → Rigveda

" Here is an excerpt of a mantra from the Rigveda, which was probably inserted in the text c. 1000 BCE, to be chanted by the priest while conducting the marriage ritual. It is used in many Hindu weddings even today:

I free her from here, but not from there. I have bound her firmly there, so that through the grace of Indra she will have fine sons and be fortunate in her husband’s love"