Answer:
"Women are better at cooking than men are." is a stereotype.
Explanation:
The other three answers are not stereotypes because they are either measurable or true.
"There are many students in that class." is not a stereotype because the sentence is talking about the specific class, and can be true.
"There are many families eating at the restaurant." is not a stereotype. It is about the same as the first option. The sentence is talking about a specific restaurant.
"Babies need someone to take care of them." is not a stereotype. It is a true statement.
"Women are better at cooking than men are." is a stereotype. Both men and women can be good at cooking. The sentence is a stereotype because it is made on assumptions and generalizations.
