The passage suggests that Smetacek regarded the death of the alga bloom described in lines 61–65 as 

A) Vindication of his theory that iron fertilization can lead to carbon sequestration. 

B) An indication of the potential dangers of “dead zones” such as those in the Gulf of Mexico. 

C) Evidence that there was insufficient oxygen in the Southern Ocean to support large blooms. 

D) A disappointment because the diatoms were being removed from the food chain.