Code § 382 Limits the Deductibility of NOLs Acquired from Loss

Code § 382 limits the deductibility of NOLs acquired from loss corporations, if there has been a substantial change in ownership-a so-called "ownership change." In which one of the following situations has ownership change occurred?

A) R owns 1,000 shares of Q Corporation.Q Corporation has 1,000 shares outstanding.R sells 400 shares to S Corporation.
B) Same as above, except Q Corporation issues 200 shares each to T and U later that same year.
C) M owns 10 percent of Loss Corporation.She purchased additional stock, increasing her ownership to 15 percent.
D) Loss Corporation, publicly held, has been actively traded such that there has been a complete change in ownership.At no time did one shareholder own more than 5 percent of stock.