Which word would best fill the blank related to expressing approval or praise?

The word "Approbation" is the most suitable choice for expressing approval or praise. It denotes a positive acknowledgment, often conveying formal or official approval of something. By using this term, a writer can communicate a sense of endorsement or validation, which aligns perfectly with the context of expressing appreciation.

In contrast, "Condemnation" refers to expressing disapproval or criticism, which is the exact opposite of approval or praise. "Obfuscation" implies making something unclear or confusing, lacking any inherent connotation of approval. "Intervention" denotes the act of intervening or becoming involved in a situation, but does not imply approval or praise in any form. These distinctions highlight why "Approbation" is the best fit for expressing positive affirmation in the given context.