Which of the following is a necessary requirement for entering a guilty plea?

For an individual to enter a guilty plea, it is essential for them to understand the charge against them. This understanding is crucial because it ensures that the defendant is making an informed decision about their plea. The legal system requires that defendants comprehend the nature of the charges, the associated rights they are waiving, and the potential consequences of their plea. This understanding helps protect the integrity of the judicial process and ensures that the defendant's rights are upheld.

In the context of the other options, having legal representation is typically encouraged, but it is not a strict requirement for entering a guilty plea. Likewise, being under arrest is not a prerequisite because individuals can plead guilty even if they are not currently in custody, provided they are charged. Lastly, the requirement to present evidence at trial is not applicable when entering a guilty plea, as the plea itself resolves the case without the need for a trial. Therefore, understanding the charge is vital and foundational for ensuring that a guilty plea is valid and informed.