It was raining , but we could n't be stopped . Our hair was flying every which direction and I was driving 15 miles over the speed limit while thinking I needed a cigarette and singing " Stop me if you think that you ' ve heard this one before , " when Carina looked over at me with her feet on the dash , " Can we have a pause moment right now ? " she asked .

Available choices: [i] The road is winding and unsafe for high speeds .. [ii] None of the above choices .. [iii] The road is buckling under the high speeds .. [iv] The road is slippery ..
Answer the following question: Why may driving conditions have worsened ?
[iv]