<span>. Estuaries have been called the "nurseries of the sea" because the protected environment and abundant food provide an ideal location for fish and shellfish to reproduce. Most commercially important fish species spend some part of their life cycle in estuaries. Besides fish, many species of birds depend on estuaries for food and nesting areas. Migratory birds use estuaries as stopover points for resting and feeding before continuing their journey. Marine mammals also use estuaries as feeding grounds and nurseries.</span>
The evaluation of their DNA and short tandem repeats will let them know if the birds are related or not. The genetic linkage will provide information about their common ancestry as well as if they belong to the same species, or are closely related species.
The answer is A . nucleus and the cytoplasm.
