Which of the Following Statements Concerning Isomers Is/are Correct

Which of the following statements concerning isomers is/are correct?
1) Two types of stereoisomers exist: geometric isomers and optical isomers.
2) Optical isomers are molecules with nonsuperimposable mirror images.
3) Ethanol (CH₃CH₂OH) and dimethyl ether (CH₃OCH₃) are examples of geometric isomers.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2,and 3