would go for C

A. inconsistent use of "it" and "one"

B. inconsistent use of "it" and "one"

C. correct IMO, consistent use of pronoun "it"

D. detect when a condition is .. wrong usage imo. when is used for time

E. detect the presence is redundant and wordy.

(B) when a condition is present and indicate that there is one

mixes there and it when referring back to the condition

(C) a condition when it is present and indicate that it is present

Its more parallel construction and brings out the contrast better than b and also uses it consistently to refer to the condition

"Detect a condition" is the most logical and not detect when a condition.
C clearly staees what the original sentence is intending to say in aclear and concise way.

Choose C

Thanks ScoobyDooby

and Thanks a lot Cramya.

"Detect a condition" is the most logical and not detect when a condition.
C clearly staees what the original sentence is intending to say in aclear and concise way.

You always provide a different view to attack the questions
thanks again