Which of the following types of crimes involves a planned agreement to commit an offense?

The type of crime that involves a planned agreement to commit an offense is conspiracy. This crime is characterized by two or more individuals coming together with the intent to commit a crime at some point in the future. The essence of conspiracy lies not only in the agreement itself but also in the specific intent to carry out the crime, even if the crime has not yet been completed or even attempted.

For conspiracy to be established, there must be a clear agreement between the parties involved and an intention to pursue a criminal objective. The law recognizes that the planning and assembly of individuals for such purposes pose a potential threat to society, hence the severity of the charge.

The other options, while related to criminal activities, do not involve the concept of a planned agreement to commit an offense in the same way. Attempt refers to taking substantial steps toward committing a crime but not achieving the completion of that crime. Solicitation involves encouraging or requesting someone to commit a crime, which again does not require a mutual agreement or plan. Negligence, on the other hand, pertains to a failure to exercise reasonable care, which doesn't involve intention or agreement to commit a crime. Thus, conspiracy distinctly encompasses a planned agreement involving multiple parties aimed at engaging in criminal behavior.