Step 1: Refer to Section 4 of the Indian Contract Act, 1872.
Communication of a proposal is said to be complete when it reaches the person to whom it is made. That is, when the offeree becomes aware of the offer.
Step 2: Apply this principle.
Only when the person to whom the proposal is made knows about it, can it be acted upon or accepted. Any other form of communication (e.g., to a third party or unknown to the offeree) is not valid.
Conclusion:
Therefore, the communication of a proposal is complete when it comes to the knowledge of the person to whom it is made.