「どちらが正しいのかわかりません」って英語でなんて言うの？

When there is a clear choice to make involving just two possibilities, in any situation, you can say: "It's either one or the other." It means the choice is only two, or, of all the possible choices, there are only two. in that case you many not be sure which is right. It's quite possible that both options are correct but one is 'more correct' than the other. In that case, you may declare: "I'm not sure which is the best answer."

"I don't know which one is the right answer." This explains to the person that out of the to options/answers you do not know which one is the right one. "I'm not sure of the correct answer." This is another way of explaining that you do not know which of the two answers are correct.

Being in two minds...figuratively means "you cannot decide.. between options offered! It could be this dress... or that dress? ... Described as an "Either or?" situation... I am not sure what to do for the best"..".I am two minds about it"

Sure' is to be completely certain about something.. 'Unsure' is to be uncertain about something. To say you are "not sure" is a perfectly acceptable and simple way to say you are unsure. If you would like to elaborate further on your thoughts, you can insert the word 'entirely' or 'completely' before the word sure, to show that you are unsure. You could also say 'which one is right' or 'which one is wrong' at the end, as you don't know what the answer is, but it has to be either right or wrong, since there are only these two options given in the question.

Of course if you don't know you can always say "I don't know". But if you would like to be more specific and correct, you can say, "between the 2 options, I'm not sure which one is correct". If there are only 2 options, then 1 has to be right and the other has to be wrong. You can say right and wrong, or you can say correct and incorrect. "I don't know..." is used more and quicker. while "I'm not sure..." is softer, a bit more elegant, but they have basically the same meaning.

If you have been given a question and you have to choose between two possible answers that have been given, and the two possible answers are almost the same, it can be quite confusing. You can either waste a lot of time figuring out the correct one or make a quick choice and move on. In a situation like this, you may say: I can't really tell which one of the two is correct. or I don't know which one of the two is correct.

The easiest answer would be 'I don't know'. You can say 'I don't know which one is correct' But native English speakers do not like to use sentences that are longer than they need to be. This means we will make it a short answer like 'I don't know' or 'I'm not sure'. If you would like to be more polite, you can say 'I'm sorry, I don't know' I hope this is helpful!