Base your answer to question 46 on the passage

below and on your knowledge of social studies.

…The deposits of fine sediment left by natural

floods sustain the fertility of floodplain soils. The

5,000-year history of agriculture in the Nile Valley

and delta of Egypt depended on the annual Nile

River flood that left a veneer of new silt over the

valley floor each year. Modern dams on the Nile

— particularly the Aswan High Dam, which can

store the entire annual flood — have destroyed

the natural system of fertilization, necessitating

huge imports of artificial fertilizers.…

— Oberlander and Muller, Essentials of Physical Geography

Today, Second Edition, Random House, 1987

Based on this passage, a valid conclusion would

be that

(1) natural fertilizers are less effective than

artificial fertilizers

(2) technological advances sometimes create

unforeseen problems

(3) yearly flooding is harmful to Egyptian

agriculture

(4) farmers in the Nile Valley operate at a

subsistence level