You have to evaluate the slopes of these lines. For line AB you have a slope of
[tex] \frac{1 - ( - 3)}{0 - ( - 3)} = \frac{4}{3} [/tex]
For line CD you have a slope of
[tex] \frac{ - 1 - ( - 5)}{3 - 0} = \frac{4}{3} [/tex]
Because the slopes are equal and the two lines are not one and the same, they are parallel.
