Is it A? No, because a right triangle does not have all three sides with equal length. Only in a equilateral triangle will have all three equal sides of equal length.
Is it B? No, because a triangle has ZERO parallel lines. Remember parallel lines are like this | | in a triangle the lines are like this /\
Is it C? Yes, because a triangle has two sides of equal length, meaning it has two congruent sides.
Is it D? Yes, a right triangle has two sides that create the 90 degrees making it a right triangle. Perpendicular means that theirs two lines creating the 90 degree and a triangle has two perpendicular sides.
