For 1-methoxy-1, 3-butadiene, which of the following resonating structure is least stable?
A. `overset()(C)H_(2)-overset(o+)(C)H-CH=CH-O-CH_(3)`
B. `overset()(C)H_(2)-CH=CH-CH=overset(o+)(O)-CH_(3)`
C. `CH_(2)=CH-overset(o+)(C)H=overset()(C)H-O-CH_(3)`
D. `CH_(2)=CH-overset()(C)H-CH=overset(o+)(O)-CH_(3)`
