Plankton generally thrive in areas of the ocean with sufficient concentration of certain nitrogen compounds near the surface, where plankton live. Nevertheless, some areas, though rich in these nitrogen compounds, have few plankon. These areas have partucularly low concentration of iron, and oceanographers hypothesize that this shortage of iron prevents plankton from thriving. However, an experimental release of iron compounds into one such area failed to produce a thriving plankon population, even though local iron cocentrations increased immeduately.
which of the following, if ture, argues most strongly against concluding, on the basis of the information above, that the oceanographers' hypothesis is false?
A. Not all of the nitrogen compounds that are sometimes found in relatively high concentrations in the oceans are nutrients for plankton.
B. Certain areas of the ocean support an abundance of the plankton despite having particularly low concentration of iron.
C.The release of the iron compounds did not increase the supply of nitrogen compounds in the area.
D. A few days after the iron compounds were released, ocean currents displaced the iron-rich water from the surface.
E. The iron compounds released into the area occur naturally in area of the ocean where plankton thrive.
正确答案是D。我选的是B
根据这道题的问法，到底是要削弱什么呢？是“海洋学者的结论” 还是 “海洋学者的结论错误”？ | 
