Answer:
(E) with children whose parents are native English speakers
Step-by-step explanation:
Compared with is used for objects whose similarities have a close resemblance, while compared to is used in comparing objects who have a wide gap in similarities. Also, in the context above, the comparison is between children whose parents speak English as a second language and parents whose parents speak English as a native language. Option E provides an appropriate comparison of the relevant subjects.
So it would be right to say, "Studies of test scores show that watching television has a markedly positive effect on children whose parents speak English as a second language, as compared with children whose parents are native English speakers".