New and interesting research conducted by Suleiman A. Al-Sweedan and Moath Alhaj is inspired by their observation that though there have been many studies of the effect of high altitude on blood chemistry, there is a blank studies of the effect on blood chemistry of living in locations below sea level, such as the California towns of Salton City and Seeley.
Which choice completes the text with the most logical and precise word or phrase?