Question

Sets $A$ and $B$ are equivalent if ___

• A. $A$ and $B$ are equal.
• B. $n\left(A\right)=n\left(B\right)$
• C. $n\left(A\right)<n\left(B\right)$
• D. None of the above.

Answer 1

Answer: (A), (B)

The correct options are
A $A$ and $B$ are equal.
B $n\left(A\right)=n\left(B\right)$

Two sets are said to be equivalent if they have the same number of elements, i.e. if their cardinalities are the same.
Thus, sets $A$ and $B$ are equivalent when $n\left(A\right)=n\left(B\right)$
If two sets are equal, then they will have the same number of elements, hence they will be equivalent.