Definition: In this task, you need to write a topic word from the given fact. The topic word must have at least one word overlap with the given fact. The topic word often involves adding a new word from a related concept. In your topic word, use at least one word from the given fact. Topic words with two or more words work best.

Positive Example 1 -
Input: Fact: pesticides cause pollution.
Output: pollution harms.

Positive Example 2 -
Input: Fact: pesticides cause pollution.
Output: modern farming pesticide.

Negative Example 1 -
Input: Fact: pesticides cause pollution.
Output: computer harms.

Negative Example 2 -
Input: Fact: pesticides cause pollution.
Output: toopaste helps.

Now complete the following example -
Input: Fact: sound can be used for communication by animals.
Output: 


Output:
Sound is frequency.
animal mammal.
animals communicate sound.
animals communicate to find mates.
animals goat.
animals sound use.
animals sounds.
barking communication.
communication bark sound.
howling communication animals.
sound vibrations.
sound waves.
vocal wolves sound.