I think the answer would be the first one.
Answer:
"A particular form of a language which is peculiar to a specific region or social group." (Google dictionary). So I would say the answer is A. But C is also a reasonable answer.
Answer:
Good personal hygiene is one of the most effective ways to protect ourselves and others from many illnesses, such as gastroenteritis.
Wash your hands regularly, especially before preparing or eating food and after going to the toilet.