Nasha is a 28-year-old lady who inherited a collection of German antique dolls from her aunt, Pn. Salmah who died last month. According to her aunt's lawyer, the collection had been valued at RM15, 000. On 1^st September 2019, Nasha contacted the Doll Collectors Association in her area and wrote the following letter to several doll collectors who are members of the association and well known for their fondness for German antique dolls.

Dear Doll Collector.

I now own a collection of twelve German antique dolls that I wish to sell at RM 15,000. I will sell them to the first person who contact me and is serious about buying the collection. This offer will be open until 30" September 2019. If you want to inspect the dolls, I will be happy to arrange an appointment with you at my house. Call me at 019-3337752. Sincerely, Nasha Azeez.

On 4^h September, Adibah, who is familiar with the collection, received the letter and immediately called Nasha to arrange inspection of the dolls on the same day. Adibah showed up at Nasha's house, inspected and photographed the dolls. She told Nasha, "I'm very interested, but I want to do some research. I'll get back to you." Nasha said, "Okay, but my letter went out to a number of other people. I'm selling to the first one who calls and confirm that he or she wants to buy the entire collection at my price." On 5'hSeptember, Adibah took the photographs to an expert doll appraiser to evaluate and authenticate the collection. The appraiser told Adibah the dolls are certainly authentic and worth at least RM 30,000 in the open market. Adibah immediately telephoned Nasha, but the call went unanswered. Therefore, Adibah left a message on Nasha's voice mail saying, "This is Adibah. I really like the dolls. Please call me at 012-7757874 when you get this message."

Later that afternoon, just to be sure, Adibah wrote a letter to Nasha stating, "I accept your offer to sell your doll collection for RM15,000. I will arrange for immediate payment and will come and collect the doll within the week. Signed, Adibah Khalid" and posted the letter at 3.00pm on 5t" September.

Soon after Adibah returned home from the Post Office, she received a phone call from Nasha. Nasha said, "I got your voice mail message. I want to let you know that I've had an appraisal made of the collection and it turns out that the dolls I have are indeed very rare and valuable. So, I'm sorry to say that I can no longer sell to you at the old price. However, dolls are just not my thing, so I still want to sell them off, but I'm not willing to let it go for less than RM35, 000." Adibah responded, "You can't do that. I have accepted your offer of RM 15,000, so we have a valid contract and I will sue you if the dolls are not mine for RM15,000".

Is there a valid and enforceable contract between Nasha and Adibah for the sale of the dolls at RM 15,000? Justify your answer with the appropriate legal principles and cases relating to contract law.