I. When two or more languages merge together to form a new language. ii. When one language breaks into different dialects and eventually breaks into different languages. iii. When there is a lack of interaction between speakers of the same language. iv. When there is constant interaction between groups that speak different languages. A. i. And iv. B. ii. Only iii. C. i., ii., and iii. D. i., ii., iii., and iv.