Sentence Correction

GMATGuruNY wrote:

Any medical test will sometimes fail to detect a condition when it is present and indicate that there is one when it is not.

(A) a condition when it is present and indicate that there is one
(B) when a condition is present and indicate that there is one
(C) a condition when it is present and indicate that it is present
(D) when a condition is present and indicate its presence
(E) the presence of a condition when it is there and indicate its presence

In A, both one and it seem to refer to a condition.
The result is a nonsensical meaning:
Any medical test will sometimes indicate that there is ONE CONDITION when A CONDITION is not.
Eliminate A.

B and D distort the meaning by implying that the purpose of a medical test is to detect a MOMENT IN TIME: WHEN a condition is present.
The purpose of a medical test is to detect the CONDITION itself, not WHEN the condition is present.
Eliminate B and D.

In E, the first it could refer to the presence or to a condition.
Since C avoids this issue and is free of errors, eliminate E.

The correct answer is C.

The OA:
Any medical test will sometimes fail to detect a condition when it is present and indicate that it is present when it is not [present].
Here, each instance of it has the same, clear referent: a condition.
Note the use of ELLIPSIS: the word in brackets is omitted, but its presence is clearly understood.
The ellipsis is made clear by the PARALLEL FORMS: that IT IS PRESENT when IT IS NOT [PRESENT].
Only the OA offers these parallel forms at the end of the sentence.

notyet wrote:Hi�Guru
I now understand the problem from the perspective of pronoun! Thanks
But C just still seemed so unparallel to me ?

choice C: verb n vs verb clause
choice E: verb n vs verb n

GMATGuruNY wrote:

notyet wrote:Hi�Guru
I now understand the problem from the perspective of pronoun! Thanks
But C just still seemed so unparallel to me ?

choice C: verb n vs verb clause
choice E: verb n vs verb n

The analysis in red is not quite right.

C: Any medical test will sometimes fail to detect a condition...and [will sometimes] indicate that it is present
Here, the words in brackets are omitted but implied.
The blue portion serves as the direct object of will fail.
The red portion serves as the direct object of will indicate.
Each of these direct objects includes a verb form.
Verb form in the blue portion: to detect.
Verb form in the red portion: is.

E: Any medical test will sometimes fail to detect the presence...and [will sometimes] indicate the presence.
Here again, the words in brackets are omitted but implied.
The blue portion serves as the direct object of will fail.
The red portion serves as the direct object of will indicate.
While the blue portion includes a verb form -- to detect -- the red portion does not.

Since the red portion in E does not include a verb form, the parallelism in E is inferior to that in C.
Eliminate E.

notyet wrote:Thanks! "Fail vs indicate" makes much sense !
But I consider "that is ..." to be a clause ,rather than a verb "is" ?