The direction cosines of the line joining the points (1, 1, -1) and (2, 3, 1) are:

• A. \(\frac{1}{3},\frac{2}{3},\frac{1}{3}\)
• B. \(\frac{1}{3},\frac{1}{3},\frac{1}{3}\)
• C. \(\frac{1}{3},\frac{2}{3},\frac{2}{3}\)
• D. \(\frac{1}{3},\frac{1}{3},\frac{2}{3}\)