If I say 'OK' after being shown more than one option, have I chosen?

No, not necessarily. When you are shown more than one way to split your money, a word like 'OK' or 'fine' can mean you understood, that you agree with one of them, or that you want to end the conversation. That is why a clear choice means naming the option you picked: the first or the second, or the letter or number on it. If you are not sure, say so plainly and take your time comparing when the money becomes available, how long it is locked, when returns get paid and the early-break terms. Note that choosing a way to split does not mean your money has been placed anywhere. Money does not move, and no account or certificate is opened for you, until you go to the bank or use its channels and sign the application for the product itself. Before signing, ask for the key-facts statement of each product in the option you chose, and check the amount, the term, the payout schedule and the early-break terms in it.