TASK DEFINITION: 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.
PROBLEM: Sentence1: Light source is an ultra-bright, unbreakable LED Bulb.
Sentence2: LEDs convert electricity into light and heat energy.

SOLUTION: LED

PROBLEM: Sentence1: a rainbow is formed by refraction of light by separating light into all different colors.
Sentence2: Rainbows form when raindrops refract sunlight.

SOLUTION: refraction

PROBLEM: Sentence1: if an animal lives under ground then that animal will be protected from a wild fire.
Sentence2: An animal living underground will be protected from an elemental part of the ecosystem.

SOLUTION:
animal