Shulte chose several areas in the lower chesapeake bay as his experimental sites. at each site, he constructed artificial reefs of two different heights. he also left portions of each site unrestored to serve as points of comparison. oysters were allowed to colonize the reefs and the unrestored bay bottom safe from harvesting. his hypothesis was that oysters would survive better in the plankton-rich upper waters away from the smothering sediments and hypoxic waters of the bay bottom. a) reef type is the independent variable. b) adult oyster density is a dependent variable. c) spat density is a dependent variable. d) high-relief and low-relief reefs are treatments.

All options are correct.

Explanation:

The scientific experiments require proper procedure and experimental set up to perform the experiments. The results and observation was used for the interpretation of the experiment.

The experiments include both the dependent variable, independent variable control and set-up. Here, Shutle used the adult oyster and reef types as dependent and independent variable. Reefs are used as treatments and Oyster density changes and included in the category of density dependent variable.

Thus, all given options are correct.

answer; the correct answer is desert plants;

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.