It is important to understand the entry requirements because it states everything you will need to know beforehand. It should tell you details of what it is about or what is needed for said entry.
'A' is the only sentence that displays correct grammar. "Are" should be used to refer to the plural form (in this case, bright flowers) of a noun. In the incorrect choices, "are" is referring to singular nouns, which is not grammatically correct.
Carol has a cottage by the sea.