Read the Paragraph Below and Answer the Questions That Follow

Read the paragraph below and answer the questions that follow.
(1) Most of the ingredients in cigarettes cause serious damage to health, but three of the worst are tar, carbon monoxide, and nicotine. (2) Tar, the brown, sticky substance produced by a burning cigarette, is a messy mixture of hundreds of toxic chemicals. (3) At least forty-three of those chemicals cause cancer. (4) The other two destructive substances, carbon monoxide and nicotine, contribute to heart disease. (5) Carbon monoxide prevents red blood cells from carrying a full load of oxygen. (6) Therefore, it reduces the body's oxygen supply. (7) At the same time, nicotine is not only constricting blood vessels and impairing blood flow but also stimulating the heart, making it beat faster and crave more oxygen. (8) Consequently, carbon monoxide and nicotine work together to damage the cardiovascular system.
Which of the following sentences contains a transitional expression that signals cause or effect?

A) Sentence 4
B) Sentence 7
C) Sentence 8