Let $T$ be an linear transformation from ${\mathbb R}^r$ to ${\mathbb R}^s$. Let $A$ be the matrix associated to $T$.

Fill in the correct answer for each of the following situations.

 1. Every column in the row-echelon form of $A$ is a pivot column.
 2. Two columns in the row-echelon form of $A$ are not pivot columns.
 3. The row-echelon form of $A$ has a column corresponding to a free variable.
 4. The row-echelon form of $A$ has no column corresponding to a free variable.

A. T is not one-to-one
B. T is one-to-one
C. There is not enough information to tell.