Suppose XYZ Corporation is traded on the New York Stock Exchange. XYZ's closing price on Monday is ...

Suppose XYZ Corporation is traded on the New York Stock Exchange. XYZ's closing price on Monday is $20 per share. After the market closes on Monday, XYZ makes a surprise announcement that it has obtained a major new customer. XYZ's stock will likely
A) open at $20 per share on Tuesday and then increase as more investors read the announcement in the Wall Street Journal.
B) remain at $20 per share because in efficient markets the price already reflects all information.
C) open above $20 because the positive news will result in a higher valuation even though the stock has not yet traded.
D) open below $20 because the surprise announcement creates more uncertainty.