Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Sentence1: Flowers produce seeds for reproduction. 
Sentence2: flowers require dispersal for reproduction.
Flowers

Sentence1: cold fronts cause thunderstorms as they pass by. 
Sentence2: Cold fronts cause lightning.
cold

Sentence1: if an object reflects light toward the eye then that object can be seen. 
Sentence2: Objects are seen by virtue of scattered light.

seen