Sentence Correction

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,

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

OG explain that A, B are wrong because "it" has no referent

I do not understand this explanation. pls, help me out

it is very important to understand the concept of pronoun and its antecedent.
The pronoun it must have an antecedent to which it can refer and if there is no antecedent,then the sentence is wrong. Please take a look on the options again.

a condition when it is present and indicate that there is one when it is not to whom does this one refer back to=> Medical Test or condition??
b,when a condition is present and indicate that there is one
Same prob as in A
c, a condition when it is present and indicate that it is present
Correct=> its refers back to the condition
d,when a condition is present and indicate its presence
I am still confused wth this one yet
e, the presence of a condition when it is there and indicate its presencewhom does this "it" refers to??

Hope this Helps

U have further confused it !!!

i would still go with D.. as i dont see any diffrence bw A and C

HI,,

Am still not clear on the possesive pronoun logic...

C.

D & B: it fails to detect the condition and not when a condition is present.

A :One has no ANTECEDENT to refer to.

E. Lengthy and awkward.

I still do not understand

why A and B are wrong

why "one" in A can not refer to "condition" because "it" in C can refer to "condition" not to "medical test"

we have to use one kind of pronoun "it" or "one" in a sentence. we can not use both kinds of pronoun "one" and "it" . Is this right?,,, Pls, help