Which of following statements is correct about Index in RDBMS$?$

Index works like the way that a library keeps books in order so that people can quickly find a book.

Index works like the way that a fast food store puts customers in a queue so that people get served in a first$-$in$-$first$-$out manner.

Index works like the way that a grocery store displays products by category so that people can easily access similar grocery items.

Index works like the way that stars spread out in the galaxy space so that human being cannot easily reach anyone of them.