What names is given to those species :
b) That have died out completely ?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the name given to species that have completely died out.

2. **Definition of Extinction**: The term used for species that have completely died out is "extinct species." Extinction refers to the termination of a kind of organism, meaning that there are no living individuals left of that species.

3. **Clarifying Extinction**: Extinction occurs when the last individual of a species dies. This can happen due to various reasons, including human activities, natural disasters, or changes in the environment.

...