You are presented with the question "What is required for plant reproduction?" and the following answer choices: 
- By wind and rain
 - Something that is found on a cloud
 - fertilization occurs
 - Males and females
 - Something that comes from a volcano
 - Something that is invisible
 - Something that causes allergies
 - sperm and egg fuse

Now knowing that plant reproduction often requires pollen and hay fever or pollen allergy is the most prevalent allergy, choose the best answer.


 

       Something that causes allergies  