Sentence Correction

Geologists believe that the warning signs for a major earthquake may include sudden fluctuations in local seismic activity, tilting and other deformations of the Earth's crust, changing the measured strain across a fault zone, and varying the electrical properties of underground rocks.

(A) changing the measured strain across a fault zone and varying
(B) changing measurements of the strain across a fault zone, and varying
(C) changing the strain as measured across a fault zone, and variations of
(D) changes in the measured strain across a fault zone, and variations in
(E) changes in measurements of the strain across a fault zone, and variations among


in option A and B changing and varying are acting as gerunds(noun forms)?

which one is preferable A or B?

vishalwin wrote:Geologists believe that the warning signs for a major earthquake may include sudden fluctuations in local seismic activity, tilting and other deformations of the Earth's crust, changing the measured strain across a fault zone, and varying the electrical properties of underground rocks.

(A) changing the measured strain across a fault zone and varying
(B) changing measurements of the strain across a fault zone, and varying
(C) changing the strain as measured across a fault zone, and variations of
(D) changes in the measured strain across a fault zone, and variations in
(E) changes in measurements of the strain across a fault zone, and variations among

A conjunction such as and must serve to connect PARALLEL FORMS.

A gerund is a VERBing that serves as a NOUN.
Like other types of nouns, a gerund can be modified by a prepositional phrase.
Like other verb forms, a gerund can take a direct object.
VERBing + PREPOSITIONAL PHRASE and VERBing + DIRECT OBJECT are not parallel forms.

A and C: sudden fluctuations in local seismic activity, tilting of the Earth's crust, changing the...strain, and varying the electrical properties
Here, the portions in red are not parallel forms.
tilting of the Earth's crust = VERBing + PREPOSITIONAL MODIFIER.
changing the strain = VERBing + DIRECT OBJECT.
Eliminate A and C.

B: sudden fluctuations in local seismic activity, tilting of the Earth's crust, changing measurements of the strain, and varying the electrical properties
Here, the portions in red are not parallel forms.
tilting of the Earth's crust = VERBing + PREPOSITIONAL MODIFIER.
varying the electrical properties = VERBing + DIRECT OBJECT.
Eliminate B.

E: changes in measurements
Here, the implication is that a change in MEASUREMENT is indicative of an earthquake.
Not the intended meaning.
The intended meaning is that a change in the STRAIN is indicative of an earthquake.
Eliminate E.

The correct answer is D.

E: variations AMONG the electrical properties of rocks
Here, the phrase in red implies that different types of rocks exhibit different electrical properties.
Not the intended meaning.
The intended meaning is that variations IN the electrical properties are indicative of an earthquake.
In other words:
If the electrical properties CHANGE, then an earthquake is imminent.