For questions 1 to 15, select the best alternative to fill the blank spaces.
Most of us, for __9__, have eaten only one or two varieties of potatoes, __10__ Latin American farmers grow up to fifty different types. Many are __11__ suitable for our __12__ and offer good nutrition.
Scientists are working to develop new food crops to __13__ new needs. Some of these new crops __14__ developed because they are easier to grow than existing ones, __15__ because they are more resistant to disease.