18.______ to the mountain towns is often difficult because of bad roads.       
   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>