conquistador wrote:Source: gmatprep ep2

A team of researchers reported that five endangered birds species had resumed nesting or investigated nesting boxes erected by volunteers having been ferried out to the island last month.

(a) investigated nesting boxes erected by volunteers having been

(b) begun investigating nesting boxes erected by volunteers, being

(c) investigating nesting boxes, erected by volunteers,

(d) were investigating nesting boxes erected by volunteers

(e) investigate nesting boxes erected by volunteers, which


Please explain this problem in terms of meaning and concepts being tested.

A: volunteers having been ferried
NOUN + having + VERBed is ALWAYS WRONG.
Eliminate A.

A COMMA + VERBing modifier must serve to refer to the PRECEDING SUBJECT.
B: birds species had...begun nesting boxes erected by volunteers, being ferried
Here, being ferried seems to refer to bird species -- the preceding subject -- implying that BIRD SPECIES were BEING FERRIED out to the island.
The intended meaning is that VOLUNTEERS were ferried out to the island.
Eliminate B.

Parallel forms should serve the SAME FUNCTION.
C: nesting boxes, erected by volunteers, ferried out to the island
Here, COMMA + erected and COMMA + ferried are parallel forms.
As a result, both modifiers seem to refer to nesting boxes, implying that NESTING BOXES were FERRIED OUT to the island.
The intended meaning is that VOLUNTEERS were ferried out to the island.
Eliminate C.

E: bird species had resumed...or investigate
Here, there is no justification for mixing the past perfect tense (had resumed) and the present tense (investigate).
Eliminate E.

The correct answer is D.