Which of the following resonating structures of `1-`methoxy-`1`,`3`-butadiene is least stable?
A. `.^(-)CH_(2)-CH=CH-CH=overset(+)(O)-CH_(3)`
B. `.^(-)CH_(2)-overset(+)(CH)-CH=CH-O-CH_(3)`
C. `H_(2)C=CH-overset(-)(CH_(2))-CH=overset(+)(O)-CH_(3)`
D. `H_(2)C=CH-overset(-)(CH)-overset(+)(CH)-O-CH_(3)`
