According to the reading, who were“Old Immigrants”?

Which of these statements best describes the ambiguity in this excerpt

Where did the domestication of crops and animals begin?

The impeachment of president clinton by the u.s. house of representatives occurred with a. virtually all republicans supporting it, while virtually all democrats opposed it b. about two-thirds of republicans supporting it and about two-thirds of democrats opposing it c. half of all democrats and half of all republicans supporting it, while half of all democrats and half of all republicans opposed it d. virtually all democrats supporting it, while virtually all republicans opposed it