A sentence is provided in indirect speech. From the four given options, choose the one that most accurately conveys the sentence in its corresponding direct speech:

The librarian of Public library said that silence must be maintained in the reading hall.

The correct answer is: “Maintain silence in the reading hall,” said the librarian of public library.

To convert an indirect speech sentence expressing a command, rule, or obligation into direct speech, we analyze the structure and tone of the statement:

1. Analyze the Indirect Speech: The reporting clause is "The librarian of Public library said..." and the reported clause is "...that silence must be maintained in the reading hall." This expresses an imperative rule or instruction for visitors/readers in a library.

2. Identify the Direct Command/Instruction: In direct speech, a formal rule or sign posted by an authority (like a librarian) instructing people to keep quiet is expressed directly as an imperative sentence: “Maintain silence in the reading hall.”

3. Reporting Verb and Structure: When converted back to indirect speech, imperative sentences giving orders or instructions use reporting clauses like said that [action] must be maintained/done.

Therefore, the option that accurately captures the exact direct speech is “Maintain silence in the reading hall,” said the librarian of public library.