Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

[EX Q]: the occipital lobe is the back part of a mammal's brain.
[EX A]: occipital lobe

[EX Q]: molar mass is the mass of a substance that has 6.022 × 10 atoms (avogadro's number).
[EX A]: molar mass

[EX Q]: norio yoshimizu (吉水 法生, yoshimizu norio, born august 21, 1946) is a former japanese football player.
[EX A]:
norio yoshimizu