Choose the false statement about the column space of an  matrix A.
A、Col A is a subspace of 
B、A vector v is a vector in Col A if and only if the system Ax=v is consistent.
C、 if and only if the equation Ax=b has a solution for every b in .
D、 if and only if the linear transformation x mapping to  Ax  map onto  .
E、The pivot columns of the echelon form of A form a basis for Col A.