Suppose a matrix $A$ has $n$ rows and $m$ columns.

Select the best statement.

A. If $m<n$ then the $m$ columns of $A$ must span ${\mathbb R}^n$.
B. If $m<n$ then the $m$ columns of $A$ span ${\mathbb R}^n$ as long as the columns are distinct.
C. If $m<n$ then the $m$ columns of $A$ cannot span ${\mathbb R}^n$.
D. If $m<n$ then the $m$ columns of $A$ span ${\mathbb R}^n$ as long as no column is is the zero vector.
E. If $m<n$ then the $m$ columns of $A$ span ${\mathbb R}^n$ as long as no column is a scalar multiple of another column.
F. If $m<n$ then the $m$ columns of $A$ can but do not have to span ${\mathbb R}^n$.
G. none of the above