Final answer:
Option a) is the correct choice for formal writing as it aligns with the convention to use words instead of symbols for numerical values under 10 and it is assumed that the abbreviation 'APR' has been defined earlier, making its usage acceptable.
Step-by-step explanation:
In considering the correct sentence choice for formal writing, namely either: a) A consumer considering a new credit card should take the APR into consideration because it can exceed the prime interest rate by 18 percent or more. b) A consumer considering a new credit card should take the Annual Percentage Rate (APR) into consideration because it can exceed the prime interest rate by 18 percent or more. c) A consumer considering a new credit card should take the APR into consideration because it can exceed the prime interest rate by 18% or more, the final answer in 2 lines would be Option a).
As per formal writing guidelines, numerical values below 10 should be written in words. Hence, instead of using '18%', we should use 'eighteen percent'. Moreover, while abbreviations like 'APR' are acceptable in formal writing, in instances where they have not been defined previously in the text, the full term should be used before the abbreviation, as depicted in option b. Here, however, the context of the question suggests that the term has been defined and used earlier, which makes option a) the best suited for formal writing.
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