The latter two are used exactly as written while the one on the top is usually structured "she is in serious medical condition" (removing the indefinite article). Hope I could help.

B and C are correct. A is not. She has a condition and suffers from it but she is not "in" it. She is in a state.

The confusion here is because the word 'condition' can have two meanings. It can be: #1 a general term meaning 'state' This meaning follows the preposition 'in'. For example: ' The car is in good condition.' This describes its overall state: it means that it is still usable and is not rusty, worn out or damaged. We generally use this for things rather than people. #2 a specific term referring to a particular disease/illness/medical problem. This meaning follows the verb 'have' or 'suffer from'. For example: She has leukemia = She has a serious medical condition. A) She is in a serious medical condition. No. 'A serious medical condition' refers to a particular illness. You cannot be 'in' an illness. B) She has a serious medical condition. Yes. C) She is suffering from a serious medical condition. Yes NB You can't always trust upvotes and downvotes. For some reason, @jakeage's answer was downvoted, even though it is correct; @Jorish's suggestion for A is wrong, but it received a bunch of upvotes. No idea why.

B and C are correct. She suffers the condition but cannot be in it so yes A is not correct. 😇

Hello