In the following passage some of the words have been deleted. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.

The thought here is that because saliva is (1)______ alkaline, stimulating it by chewing gum after eating (2)______ help neutralize the acidity in your mouth and throat. (3)________ a very small study from 2005 did (4)_______ some merit to this approach, the size of the study makes it difficult to (5)_______ any real conclusions.