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.

Fact: a seismometer is used to measure the strength or magnitude of an earthquake.
earthquake cause.

Fact: Vesicle transport requires energy, so it is also a form of active transport.
Vesicle transport.

Fact: a plant requires nutrients to grow.

Plant nutrient.