Although blue herons can still be found along the Maine coast, their population has declined dramatically when compared to the 1970's, a period in which there were fewer bald eagles competing with them for food and nesting sites.

A their population has declined dramatically when compared to the 1970s
B their population has declined dramatically compared with the 1970s
C their populations have declined dramatically since the 1970s
D their populations have declined in comparison to those of the 1970s
E their population has declined in comparison with that of the 1970s


Pls provide your answer with explanation