In the following questions, read the pasage carefully and choose the best answer to each question out of the four alternatives
PASSAGE
STEM:
Half a century ago, a person was far more likely to die from heart disease. Now, cancer is the No. 1 cause of death. Troubling as this sounds, the comparison is unfair. Cancer is, by far the harder problem a condition deeply ingrained in the nature of multicellular life. Given these obstacles, cancer researchers are fighting and even winning smaller battles : reducing the death toll from childhood cancers and preventing and sometimes even curing cancers that strike people in their prime. But when it comes to diseases of the eld erly, there can be no decisive victo ry.
The diseases that one killed ear Hier in life bubonic plague, smallpox, influenza, tuberculosis were easier obstacles. Each had a precise cause that could be confronted. The toll of heart diseases has been pushed into the future, with diet, exercise and medicine that help con trol blood pressure and cholesterol. Because of these interventions peo ple between 55 and 84 are increas ingly more likely to die from cancer than from heart disease.
"Cancer is by far the harder problem". (Improve the sen tence)

Options

A. a toughter problem
B. a more difficult problem
C. a firmer problem
D. the most complex problem

Answer

B