Verbal Ability - Change of Speech - Discussion

Option A and C is a little bit confusing and definitely, it is not b or d. Because in B, it is not mentioning servant. D is not correct.

C is the correct one. It has captured the following aspects of the original sentence:
Nita is the one who said it.
She ordered her servant to bring the tea.
The tea is for her (Nita).

While in A.
Nita is the one who said it.
She ordered her servant to bring the tea.
BUT It is unclear for whom is the tea (could be for Nita, or for someone else like a guest, maybe)

B and D are definitely incorrect.

When do we use "told" and when do we use said to? please anyone explain me.

Told is for past tense the that happen already and said is for present the thing that are happeninig now.

Option C is correct because the question is given in past tense and now we have to select for a present so option A D are cut and option C cut because her servant is mention in question so it should be present in the answer. Hence B is correct.

Option C is the correct answer.

Option A is correct because we always use "told" at the time of order. So option A is correct.