The benefits of the new policies are
far reaching, economic experts say, providing a powerful vehicle to chip away at poverty in other countries and expanding the earnings of immigrants in the United States.
A)far reaching, economic experts say,
providing a powerful vehicle to chip away at poverty in other countries and
expanding the earnings of immigrants in the United States.
Correct. "providing" and "expanding" modify "the benefits" correctly.
B)far reaching, economic experts say, as
it is providing a powerful vehicle to chip away at poverty in other countries
and expand the earnings of immigrants in the United States.
Wrong. "The benefits" is plural. Bad grammar structure.
C)far reaching, economic experts say,
providing a powerful vehicle to chip away at poverty
and expand the immigrants’ earnings in the United States.
Wrong. Not parallel.
D)far reaching, economic experts say, by
providing a powerful vehicle to chip away at poverty in other countries while
it expands the earnings of immigrants in the United States.
Wrong. Parallelism problem + "The benefits" is plural.
E)far reaching, economic experts say, in that
they provide a powerful vehicle to chip away at poverty in other countries
expanding the earnings of immigrants in the United States.[/quote]
Wrong. "They" refers to the benefits or experts? + Parallelism problem.
Hope it helps.