Serena's jokes were always more offensive when she was at soccer practice than when she was in class. The best phrase is "more offensive" (A) because it is a comparison.
The correct answer is A, 'more offensive,' as it properly compares the jokes Serena tells in two different settings. This comparative form is appropriate for an adjective with two syllables. The other options either use incorrect forms or are superlatives not suitable for this comparison.
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