To test the potential effect of hunger on taste sensitivity, groups of research participants are deprived of food for differing lengths of time before they engage in a taste-sensitivity test. This research is an example of

Experimental research

Explanation:

Experimental research is a scientific approach to research one or more independent variables are varied and applied to one or more dependent variables to measure the effect of the independent variable on the dependent variable. Experimental research is normally done when a relationship between variable (i.e independent and dependent) is needed to be determined. It includes a hypothesis, a variable that can be manipulated by the  researcher, and variables that can be measured, calculated and compared.

answer; /// i believe that the correct answer is (a) making presentations;

explanation:

with the profits from the european sales, merchants purchased europe's manufactured  goods, including tools and weapons. then the merchants shipped those manufactured  goods, along with the  american  sugar and rum, to west africa where they were bartered for  slaves.