问题：
[多选题]Company A and Company B signed an agreement on cooperation and development, saying that the mutually developed area A’s properties belongs to company A and area B’s properties belongs to Company B. Company B then signed a power of attorney with company C authorizing company C to sell the properties owned by company B. The power of attorney has company B’s seal and company B’s legal representative Wang’s signature on behalf of the principal. Wang is also the legal representative of Company A. Zhang checked the cooperation and development agreement and the power of attorney, then signed a property pre-purchase contract with company C, and agreed the following: “Zhang pay a deposit of 300,000 yuan to purchase a property in area A. When the property receives the sale permit then the two parties will sign a formal sales and purchase contract.” Company C used the 300,000 for investment and lost the full amount. Wang issued a “letter of commitments” to Zhang saying that: “If Zhang does not create any trouble, Wang will coordinate with company A to sell the property to Zhang.” When company A received the sales permit, it sold all the property to other buyers. Zhang requested Company A, B, and C to return the deposit. Zhang then signed a “creditor’s rights transfer agreement” with Li, and transferred the credit to Li. Zhang notified company A, B, and C. Li did not pay the creditor’s rights transfer cost in time, therefore Zhang transferred the credit to Fang and also notified company A, B, and C.
Please answer questions 1 -3 below.
About “The power of attorney” and the “Letter of commitments”, which of the following descriptions is correct:
A、Company B is the principal.
B、Company B and Wang are joint principals.
C、Company A, Company B, and Wang are joint principals.
D、“Letter of commitments” does not have any legal effect.
