If the line is passing through the points ((x_1, y_1, z_1) ) and has direction cosines l, m, n of the line, then which of the following is the cartesian equation of the line?

• A. ( frac{x-x_1}{l}= frac{y-y_1}{m}= frac{z-z_1}{n} )
• B. ( frac{x-x_1}{n}= frac{y-y_1}{m}= frac{z-z_1}{l} )
• C. ( frac{x+x_1}{n}= frac{y+y_1}{m}= frac{z-z_1}{l} )
• D. ( frac{x+x_1}{l}= frac{y+y_1}{m}= frac{z+z_1}{n} )