One of the earliest developments in the field of nutrition linking nutritional deficiency to illness was the discovery that eating citrus fruits prevents: . scurvyb. pellagrac. cancerd. strokes

The correct answer is a. scurvy

Explanation:

Scurvy is a deficiency disease which is caused by the deficiency of vitamin C. James Lind in the 18th century discovered that citrus fruit prevents scurvy and can help in curing the scurvy.  Scurvy was the main cause of death in sailors during long-distance sea travells.

Citrus fruits have plenty of vitamin C which is required for in variety of biosynthetic pathway and lack of vitamin-C cause weakness, gum disease, anemia, and skin problems.   So eating citrus fruits prevents scurvy.

because health skills are tools and strategies and also practical skills are also something you need to learn (like tools and strategies) and put it in reality.