As a politician who gave higher priority to political harmony than to territorial expansion, Martin Van Buren rebuffed Texas' request for annexation because he feared
A. the struggle between North and South leading to a dissolution of the Union
B. the bitter struggle over the price of land offered to new settlers
C. the initial reaction by the Native Americans living in the surrounding states
D. the expensive financial restitution needed to be paid to Mexico
E. the overwhelming Mexican population attempting immigration into the U.S.