List the Elements of the Set $\mathrm { A } \cup \mathrm { B } \text {. }$

Multiple Choice

List the elements of the set.
-If A={21,23,24,25,28} and B={21,23,24,25} , list the elements of $\mathrm { A } \cup \mathrm { B } \text {. }$

A) {28}
B) {21,23,24,25}
C) $\phi$

D) {21,23,24,25,28}