18.______ to the mountain¹ towns² is often difficult³ because⁴ of bad roads⁵.       

   A. Aversion   B. Orison   C. Incentive   D. Access

<aversion>

aversion  厌恶，嫌恶，讨厌的

</aversion>

<orison>

orison  祈祷

</orison>

<incentive>

incentive  刺激，奖励 (跟金钱有关)

</incentive>