Answer: A language shift
Step-by-step explanation:
According to the given question, Demetrius's family immigrated from Ukraine to the united states and his parents observed that his native language is not good but he was fluent in English.
This above given scenario was exhibiting a language shift as it is the process of replacement of the language during the period of time.
It is due to the influenced from the surrounding community where the people used the English language for the communicating and interaction purpose.
The following are some causes of the language shift are as follows:
- Social factor
- Economic factor
- Values
- Demographic factor
Therefore, Language shift is the correct answer.