Which category is this book classified under?

The folk etymology of this word is very interesting.

Rigor mortis is the phenomenon where part or all of the body stiffens after death.

Her face is a beautiful oval shape.

He made up his mind to face the difficulties.

He gave me an ultimatum.

I saw a flamingo in the park.

He started writing a song on the staff notation.

A kana ligature is one of the notation methods in Japanese.

Nishikori is my friend.