Which definition best describes 'sanction' in terms of permission?

The definition that best describes 'sanction' in terms of permission is to 'authorize or grant.' In this context, the term 'sanction' refers to the act of giving official approval or permission for something to occur. This meaning illustrates the acceptance or endorsement of an action or decision, indicating that it is permissible under certain conditions.

The other options relate to different meanings of the word 'sanction.' For example, to 'enforce a restriction' suggests a punitive or prohibitive context, which contrasts with the idea of granting permission. The meanings associated with 'express an opinion' and 'provide a critique' focus on personal viewpoints and assessments, which do not align with the notion of official approval or authorization.