In this question,i marked the first option but the answer sheet says that the third option is correct.Why do we need to repeat 'that' everytime?
What concern scientists the most about global warming are the risks that the polar ice caps will melt,
the seas will grow too warm to sustain marine life, and that violent weather patterns may result.
• are the risks that the polar ice caps will melt, the seas will grow too warm to sustain marine life, and
that violent weather patterns may result
• is the risks that the polar ice caps will melt, that the seas will grow too warm to sustain marine life,
and that violent weather patterns may result
• are the risks that the polar ice caps will melt, that the seas will grow too warm to sustain marine life,
and that violent weather patterns may result
• is the risks that the polar ice caps will melt, the seas will grow too warm to sustain marine life, and
that violent weather patterns may result
• are the risks of polar ice caps melting, seas growing too warm to sustain marine life, and that violent
weather patterns may result

Thanks in advance:)

Clauses starting with the same word should be made parallel.
Means Clauses should not be parallel to anything besides another clause.
Hope you got it!

oops i dint see 'that' before violent in the first option...thanks...:)

Great, thanks! Nice observation; we need "that X, that Y, and that Z" here.

_________________
Jamie Nelson
ManhattanGMAT Instructor