Diethyl ether is not associated with which one of these isomers

Structural isomers of  Diethyl ether are C2H5−O−C2H5 Diethyl ether ↔CH3-O-CH2-CH2-CH3(1-methoxy,propane)                            ↔CH3-O-CH(CH3)-CH3 (2-methoxy,propane)                           ↔CH3-CH2-CH2-CH2-OH(1-propanol)                            ↔CH3-CH2-CH(OH)-CH3(2-propanol)                             ↔CH3-CH(CH3)-CH2(OH)(2-methyl,propan-1-ol)                              ↔(CH3)3-C-OH (2-metyl,propan-2-ol) Diethyl ether does not exhibit stereo isomerism due to absence of stereo genic center.