Darius is learning the names of two or three new objects or events every day. this rapid increase in vocabulary is referred to as the

this rapid increase in vocabulary is referred to as the: NAMING EXPLOSION

Naming explosion or most commonly known as 'word spurt' is a situation where a child manage to add a lot of new words over a period of time.
This occurence most commonly happen after the child's brain has recognize the pattern of the specific language which allows him/her to understand and memorize it better.

Yes all of them are right