To answer this question, we need to understand the rules for forming plurals in English.
When it comes to the noun "formula," it has multiple plural forms.
Option A) Formula - This option is incorrect because "formula" is the singular form of the noun, not the plural.
Option B) Formulas - This option is correct because "formulas" is one of the plural forms of "formula." It is the most commonly used plural form in modern English.
Option C) Formulae - This option is correct because "formulae" is another accepted plural form of "formula." It is less commonly used but is considered the more traditional plural form.
Option D) Formidable - This option is incorrect because "formidable" is an adjective meaning inspiring fear or respect, and it is not related to the noun "formula."
The correct answer is Option C) Formulae. This option is correct because it is one of the accepted plural forms of "formula."