【单选题】

According to the passage, which of the following is characteristic of lipoproteins
A．(A) The dangers of lower density lipoproteins and the dangers of higher density lipoproteins are remarkably similar in the case of coronary heart disease.

B．(B) A higher ratio of higher density lipoproteins to lower density lipoproteins has a salubrious effect on heart disease.
C．(C) A shift from a polyunsaturated fat diet to a saturated fat diet tends to increase the risk of coronary heart disease stemming from high-density lipoproteins.
D．(D) A shift from a polyunsaturated fat diet to a saturated fat diet tends to decrease the risk of coronary heart disease stemming from low-density lipoproteins.
E．(E) Controlled feeding studies have yet to establish the feasibility of attempting to manipulate lipoprotein ratios through dietary change.