In testing the hypothesis, research observations have shown a direct relationship between higher sodium intake and higher blood pressure across population groups.
a. true
b. false

True.

Explanation:

The sodium is necessary for the proper functioning of body and maintains the electrolytes balance of the body. The sodium is also important for the conduction of nerve impulse.

Research has tested the hypothesis in the population and found that the higher sodium intake increases the blood pressure of the organism. High amount of sodium also increases the heart related disease in the individual.

Thus, the correct answer is option (a).