A biconditional statement is a statement in which it is inherently true but when the clauses are exchanged, the statement would still be regarded as true. In this case, the statement is biconditional. The answer that would make sense here would be C. Yes; if two lines are perpendicular, then they intersect at right angles.
If he goes 140 miles in 2 hours, then in 6 hours he would go 420 miles. 420 miles is not equivalent to 490 miles, so he would not reach his destination on time.