marine wrote:
By sucking sap from the young twigs of the hemlock tree, tree growth is retarded by the woolly adelgid, causing needles to change color from deep green to grayish green and to drop prematurely.
A. tree growth is retarded by the woolly adelgid, causing needles to change color from deep green to grayish green and to drop
B. tree growth is retarded by the woolly adelgid, and this causes the color of needles to change from deep green to grayish green, and their dropping
C. the woolly adelgid retards tree growth, which causes needles to change color from deep green to grayish green, and dropping
D. the woolly adelgid retards tree growth, causing needles to change color from deep green to grayish green and to drop
E. the woolly adelgid retards tree growth, and this causes the color of needles to change from deep green to grayish green, and the their dropping
Look at the opening of the sentence
'By sucking sap from the young twigs of the hemlock tree'; this is a modifier which tells us that 'Someone of something is sucked/is sucking the sap from young twigs of hemlock tree' - ask the question
'Who/What is sucking the sap?'.Then move forward to the next part of the sentence
'tree growth is retarded by the woolly adelgid''; here we will find the answer to above question - 'Is it tree growth sucking the sap'? Makes no sense. Therefore, reading the sentence till now we know that the woody adelgid sucks the sap from young twigs.
Based on this, eliminate A and B because the modified entity (which is a noun) is wrongly placed too far. Keep C, D and E. Now move forward evaluating these three choices and spotting the errors.
Note the difference in the three choices:
C: 'which causes' ; 'and dropping'
D: 'causing' ; 'and to drop'
E: 'and this causes' ; 'and the their dropping'And' is a parallelism marker. In parallelism, once you have spotted a parallelism marker, the next step is to look for parallel elements in order to verify if the marker justifies its presence in the sentence. As per the meaning of the sentence, 'The retarding of tree growth is causing the needles to do two things - change color and drop prematurely'. Now, the next step is to look for these parallel elements in the answer choice where the meaning is also clear.
C: which causes needles
to change color from deep green to grayish green,
and dropping 'to change color' and 'dropping' is not parallel
D: causing needles
to change color from deep green to grayish green
and to drop 'to change' and 'to drop' is parallel.
E: and
this causes the color of needles to change from deep green to grayish green,
and the their droppingNot parallel
Therefore
the answer choice D is correct because it shows parallelism with correct placement of markers and without distorting the meaning of the sentence