its a question from contract law

Question 1 Anna owns a shop that sells expensive watches. On 1s March Boris telephones the shop and asks if Anna would like to buy his Rolex watch. Anna says that she is 'certainly interested but would need to inspect the watch first'. On 2nd March at 10am Boris visits the shop and says: 'This is the watch; it's yours for $10,000.' Anna replies 'I like it a lot but $10,000 is too much for me.' Boris responds 'That's okay, have a think about it and I will keep the offer open until midday on 4th March.' Later on 2nd March, after Boris has left, Anna realises that the watch would make a good gift for her son's upcoming 18" birthday. She calls Boris and offers him $8,000 for the watch which Boris refuses. Anna says she will need to speak to her partner before offering any more. When they speak Anna's partner tells her that she should offer the full price. Anna immediately rings Boris and leaves a voice message saying she would like to buy the watch for E10,000 and will assume this is acceptable unless Boris tells her otherwise in the morning. She adds that she will go to Boris's house at 1pm the following day to pay for it. Boris was attending an evening business meeting when Anna rang. At the meeting Boris met Chas. Chas noticed the watch which he liked a lot and so immediately offered Boris $10,000 for it which Boris accepted. At 1pm on 3'd March Anna goes to Boris's house to collect and pay for the watch. Boris is surprised as he got home late from his meeting and overslept and so had not yet listened to his voice messages. Advise Anna