Final answer:
To clarify the word 'dazzle' as used by Reagan, a dictionary is the best choice because it provides definitions and various senses of the word.
Step-by-step explanation:
If you are considering Reagan's use of the word dazzle in paragraph 5 and you are looking to clarify the word's meaning in that specific context, the most suitable source would likely be a dictionary. A dictionary provides the general definitions of a word and its various senses, which can help you understand how it is being used in a particular piece of text. A thesaurus, on the other hand, would offer synonyms and related words but not the definition, while an encyclopedia may provide in-depth information about topics but not specific word definitions. A textbook may use the word in context but is unlikely to define it. Therefore, to clarify the meaning of the term dazzle as used by Reagan, a dictionary would be the best source to consult.