Here it is given rank of matrix $m-1$
That means there are $m-1$ non zero rows in the matrix
As, if the definition of linearly independent is the determinant of the matrix must be non-zero, otherwise in non linearly independent matrix determinant of the matrix must be 0.
Now, as the matrix has rank $m-1$ , that means matrix is a square matrix
Because, without square matrix we cannot find determinant
From here we can say, there must be $m-1$ column which are non-zero.
So, option B) is correct
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