According to the passage, the major causes of death in Frank Le Clair’s country are ( ).

参考解析：

根据第五段…two of the biggest killers in this country: coronary heart disease and stroke.可知在这个国家引起死亡的两种疾病是冠心病和中风，故正确答案是选项B。选项A都是指高血压，根据文章可知高血压只是引起各种疾病的原因，而并非引起死亡的直接病症，错误；选项C：肝脏损害和肾问题，根据文章最后一段a high salt intake can be dangerous for people with conditions…, such as hepatities, liver or kidney problems.可知这些疾病只是举例说明大量的盐摄入会在这些疾病中对人们带来死亡威胁；选项D根据文中最后一段it is also an aggravating factor in osteoporosis and is closely linked to stomach cancer.可知胃癌和骨质疏松也只是高盐摄入量可能会引起的疾病。故本题正确答案选B。