Topic: Group verb,

Best Answer Explained in Below-:

In the context of the sentence "The police will soon_____ the murder," the phrase that best fits is "look into." The expression "look into" means to investigate or examine something more closely, which is precisely what police do when they are trying to gather facts and evidence related to a crime, such as a murder.

The other options, while they incorporate the verb "look," do not convey this investigative meaning.

- "Look in" typically refers to entering a space briefly, often to check on something or someone, which does not apply to a murder investigation.
- "Look upon" implies a sense of viewing with contemplation or regard, but lacks any connotation of action or investigation.
- "Look for" suggests searching for something specific, like a person or an object, rather than the thorough investigation of a complex situation like a murder.

Thus, "look into" is the only phrase that correctly captures the police's intended action of conducting a detailed inquiry into the murder case.