992. The yield of natural gas from Norway’s Troil gas field is expected to increase annually until the year 2005 and then to stabilize at six billion cubic feet a day, which will allow such an extraction rate at least for 50 years’ production.

A) 2005 and then to stabilize at six billion cubic feet a day, which will allow such an extraction rate at least for
B) 2005 and then to stabilize at six billion cubic feet a day, an extraction rate that will allow at least
C) 2005 and then stabilizing at six billion cubic feet a day, with such an extraction rate at the least allowing
D) 2005, then stabilizing at six billion cubic feet a day, allowing such an extraction rate for at least
E) 2005, then stabilizing at six billion cubic feet a day, which will allow such an extraction rate for at least

Solution:
Parallelism
A: use of ‘which’ is ambiguous
C: 'Stabilizing' and 'expected' are not parallel.
D: 'Stabilizing', 'allowing' and 'expected' are not parallel
E: 'Stabilizing', 'will allow' and 'expected' are not parallel
B: Best choice. Parallelism maintained “....is expected to increase....and then to stabilize....six billion cubic feet a day, an extraction rate that will allow at least 50 years’ production.”


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