The choice that correctly identifies the kind of sentence and the correct end mark is option D. Declarative, period. A declarative sentence is just plainly a sentence that merely gives facts or describing someone or something. Since the sentence is a declarative sentence, the end mark should always be a period.
"Sticking" to basics such as tea, bread, and butter, also known as THE english snack. Also, all of these three produces are cheap, hence the economical.
