The correct answer is (c).
Section 167 of the Code of Criminal Procedure (CrPC) states that when a person is arrested and detained in custody, the police officer must, within 24 hours of the arrest, either release the person on bail or produce him before a magistrate. The magistrate may then remand the person to police custody for a further period of up to 15 days, or release him on bail.
Section 167 does not provide for the release of an accused person when the evidence against him is deficient. This is because the purpose of bail is to ensure that the accused person appears for trial, and not to assess the strength of the evidence against him.
The other options are correctly matched.
(a) Section 164A of the CrPC provides for the medical examination of a victim of rape. The examination must be conducted by a registered medical practitioner, and the report of the examination must be submitted to the police.
(b) Section 166A of the CrPC provides for the issuance of a letter of request to a competent authority in a country or place outside India for the investigation of an offence. The letter of request must be accompanied by a copy of the First Information Report (FIR) and other relevant documents.
(d) Section 172 of the CrPC requires the police officer conducting an investigation to maintain a diary of the proceedings. The diary must contain a record of all the steps taken in the investigation, including the names of the persons questioned, the places visited, and the evidence collected.