Usage of uncountable nouns [closed]

Which option is correct to use in this sentence and why?

I have (much, many, an) orange juice.

I agree that "many" must be incorrect. It implies a countable noun. The only instances where I think that "many" would work is where the countable noun is the container for the orange juice, such as "I have many glasses of orange juice", or "I have many bottles of orange juice". The sentence "I will have an orange juice", is what a native speaker would say when they mean, "I will have a glass of orange juice". In other words, the article "an" in the former sentence, is really an article relating to some sort of container (the glass).

If the sentence is to refer to a large quantity of the liquid orange juice itself, I expect that the most likely description would be "a lot". For example, if you have an enormous container of orange juice and someone offers you a discount on a purchase of some more bottles of orange juice, then you might say, "I already have a lot of orange juice." That is, the expression "a lot" refers to the quantity of juice, rather than to the number of containers (which might be only one) that it is stored in. "much orange juice", is grammatically correct, but a native speaker would never use the expression.

In Australian English either "an orange juice" or "many orange juice" might be spoken (and less commonly written) because "orange juice" could represent "glass of orange juice", "bottle of orange juice" or more generally "serving portion of orange juice". This is an example of synecdoche, where a part of an expression stands for the whole.

A person planning a party might ask "Do we have enough to drink?" and be answered "A few apple cider and twice as many orange juice." When asked "Would you like something to drink?", the guest replies "I have an orange juice, but thank you."

I have many orange juice is ungrammatical. I have much orange juice is grammatical, but an unlikely sentence for any native speaker to say. I have an orange juice is also grammatical and more likely to be heard in certain contexts. What any speaker or writer might actually produce depends entirely on what has gone on previously in the conversation or written text.