The correct answer is A. Only
Explanation
It is known as a modifier to words or phrases that act by modifying the core of the subject in a sentence, complementing its meaning. Among the modifiers of the subject's nucleus, there are the articles and adjectives that accompany the subject's nucleus noun, define it, and agree with it in gender and number. These modifiers are called direct modifiers. Therefore, Only is a modifier because it modifies the complete meaning of the phrase by modifying the core noun of the subject "they". So the correct answer is A. Only.
The correct answer is 'that neither logic nor superstition can fully explain cultural traditions'.
Number 4: She has six Aunts, five Uncles, and fifteen cousins, has a capitalization error.
Aunts and Uncles should be lower cased because they are common nouns. They describe the people who are the aunts and uncles. However, if you had a name that followed aunt (like in number 5), then Aunt and the name of the person would be capitalized because it is a title of a person and it becomes a proper noun.
Hopefully this helped.
Think of an equation:
200 - 91 = 109
You can do anything to this equation, as long as you do the same thing to both sides. So, if you add 91 to both sides, you will get:
200 = 200
Since this holds true, Susan's strategy to add her answer to 91 makes sense.