With reference to the planet Earth, consider the following statements:I.Rain forests produce more oxygen than that produced by oceans.II.Marine phytoplankton and photo-synthetic bacteria produce about 50% of world's oxygen.III.Well-oxygenated surface water contains several folds higher oxygen than that in atmospheric air.Which of the statements given above is/are correct?

1. A

   I and II

   I and II. Rain forests producing more oxygen than oceans is the over-claim.

2. B

   II only

   II only. Marine phytoplankton and photosynthetic bacteria produce about half of Earth’s oxygen. That is the scored line.

3. C

   I and III

   I and III. Both the rainforest-over-ocean line and the dissolved-oxygen line are the extras.

4. D

   None of the above statements is correct

   None. II holds.

Summary. Official Set A key is (b) II only. Oceans, via phytoplankton and related photosynthesizers, supply on the order of half of global oxygen — that is Statement II. Rain forests do not out-produce the oceans (I fails). Well-oxygenated surface water does not hold several-fold more oxygen than air (III fails). So only II is correct.