What is one of the largest contributors to health problems in low-income countries?

A. Veganism

B. Clean water access

C. High caloric diets

D. Sterilization

B. Clean water access

Explanation:

In the countries with comparatively lower income, tends to struggle from a lot of health issues and on the major cause of this problem is limited amount of clean water.

According to the reports, 3.4 million people die every year due to water related issues.

There are lot of problem which are associated with dirty water.

These waterborne diseases are Dysentery, Typhoid, Guinea worm disease and Cholera.

Hence, from the given statement of the question,

The correct option is B. Clean water access.