In this case, Co expected her to communicate …But you said it doesn’t have to be oral ,,,conducting is possible.. What do you think? They can’t expect her to say I’m agreeing to your offer … Like you said , buying the product indicates she agreed….
Buying the product was the action that completed the first contract – the contract of buying and selling the smoke balls.
The second contract was the “reward” contract and, in that situation, the one that offers the reward cannot expect billions of responses all saying “I accept” So, in a reward situation, the offeror waives the right of communication of acceptance