я не знал, какую

I didn't know which one

→ я
phrase Rare #45,682
I didn't know which one Used when the omitted noun is feminine singular; the following infinitive explains what action to take, such as choosing or buying it.
RU: Я не знал, какую выбрать.
EN: I didn't know which one to choose.

Я не знал, какую купить.

I didn't know which one to buy.

Я не знал, какую покупать.

I didn't know which one to buy.

Я не знал, какую выбрать.

I didn't know which one to choose.

Я не знал, какую мне покупать.

I didn't know which one to buy.