With regard to serum cholesterol levels and risk of heart disease among middle-aged people, research suggests that​

A) ​cholesterol level may not be a risk factor for cardiovascular disease.
B) ​total cholesterol to HDL ratio may be more important than total cholesterol.
C) ​low-density lipoproteins may protect people against cardiovascular disease.
D) ​maintaining a high ratio of total cholesterol to HDL is most desirable.

Research suggests that the ratio of total cholesterol to HDL may be a more important predictor of heart disease risk than total cholesterol alone. High levels of HDL (the "good" cholesterol) may protect against heart disease, while low levels of HDL and high levels of LDL (the "bad" cholesterol) may increase the risk. Therefore, maintaining a lower total cholesterol to HDL ratio is more desirable for reducing heart disease risk. The other choices (A and C) are not supported by current research evidence. D is incorrect because a high ratio of total cholesterol to HDL is actually undesirable.