The phrase from the statement that signals an opinion is A. foolishly boasts.
The word 'foolishly' is an adverb used to refer that something is done in a stupid way. Moreover, it is a word that expresses an opinion. By using this adverb together with the verb 'boast', which has a negative connotation, the author is giving an assessment of a specific situation and making a judgement. In contrast, the other options provided do not include words that express opinion. The phrases in B., C. and D. only present facts.
