A)selectivity of nest sites among cavity-nesting songbirds
B)the grass species preferred by grazing pronghorn antelope and bison
C)nitrate and phosphate uptake by various hardwood forest tree species
D)stomach analysis of brown trout and brook trout in streams where they coexist
E)selectivity of nest sites among cavity-nesting songbirds, the grass species preferred by grazing pronghorn antelope and bison, nitrate and phosphate uptake by various hardwood forest tree species, and stomach analysis of brown trout and brook trout in streams where they coexist

A)1%
B)5%
C)25%
D)33 1/3%
E)50%

A)Study the temperature range and humidity requirements of the species.
B)Observe if the niche size changes after the addition of nutritional resources to the habitat.
C)Observe if the niche size changes after the introduction of a similar non-native species.
D)Measure the change in reproductive success when the species is subjected to environmental stress.
E)Remove a competitor species to see if the species expands its range.