So that there wouldn't be to much population in the community, and so that people wouldn't be confused by two people who look identical but ultimately will live in different dwellings.
In The Giver, when identical twins are born, they are weighed and the smaller one is released. Release is a euphemism for euthanasia, which means that one of the twins is killed by lethal injection.
"<span>How many times greater is the acidity of hydrochloric acid than vinegar?" is the best option from the list, since this is what the chapter is primarily dealing with. </span>