The phrase “these years” in the third paragraph refers to

Đáp án A
The rapid transcontinentat settlement and these new urban industrial circumstances of the last half of the 19th century were accompanied by the development of national literature of great abundance and variety. New themes, new forms, new subjects, new regions, new authors, new audiences all emerged in the literature of this half century. “these years” ở đây chính là đề cập đến the last half of the 19th century (nửa cuối thế kỉ 19) ⇒ từ năm 1850-1900