Counter offer case study?

A advertised his guitar for sale at $4000. B saw it and said he would like to buy at $3000. After negotiation A agreed to reduce his asking price to $3500. He gave B 2 days to make up his mind.
The next day, B messaged A and said: "The price is OK. But is delivery included?". A read the message but didn't reply.
The following day, C who was desperate to own a guitar, called A and say he would pay for the $4000 asked as long as the guitar is in tune. A directly agreed, but he didn't hear the part about the tuning.
On Saturday, B found out that the guitar was already on sale. A told him that C is now the new owner of the guitar.
However, C now doesn't want the guitar anymore because it is out of tune.
Advise each one of them to their common law rights.

Help me please, I am stuck^^

Legally there is no concluded contract between A and B , and between A and C.
A has not replied to B and hence there is no contract between them !
There is no contract between A and C, as C as the terms of contract have not been fulfilled and the contract is voidable at the option of C , which he has exercised .

B is out of luck and has no rights. The discussion was about the price of the guitar. There was never any talk about delivery so he put the whole transaction back into the negotiation process which was never discussed since A did not contact B back.

C -- Stuck with the guitar. It is a he said/she said. The burden of proof would fall on C he/she actually made that statement during the course of the conversation. A advertised the guitar at $4,000.00 and that is what C paid. C should have text.

C can contact B to sell him/her the guitar to try and recoup some of his money. It is out of A's hands now.