Does the distribution of bases in sea urchin dna and salmon dna follow chargaff’s rules?

Yes they follows,

Explanation:

The precise response to this query would be yes. The distribution of bases in sea urchin DNA and salmon DNA follows the rules of chargaff, because% a is approximately% t and% g is approximately% c in both species. The rules of Chargaff's are used to forecast the proportion of one or more bases in the DNA of a species if at least one value is known.

protein synthesis is an example of feedback mechanism which in homeostasis

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."