What crime has Johnny committed by altering his own grade in the school’s computer network?

By altering his own grade in the school’s computer network, Johnny has committed the crime of tampering with a governmental record. The reason this choice is correct lies in the nature of educational institutions as they often operate under governmental regulations and their records are considered official documents. A school's grade records are typically maintained for the purposes of education and accountability, which places them under the protection of laws regarding governmental records. Altering such records constitutes tampering, as it is an unauthorized change to an official document that can affect the administration of education and the integrity of student records.

In contrast, while computer hacking involves unauthorized access to computer systems, that term generally applies to breaching security protocols rather than simply changing one's own data once logged in. Fraud relates to deceiving another for gain, but Johnny's act is more specifically aligned with interference with official records than deception for profit. Identity theft involves stealing someone's personal information to impersonate them, which is not applicable in this case since Johnny is modifying his own grade rather than usurping another person's identity.