(C) Yes, the number of shares held by investors increased in proportionate ratio in which a stock split.
In a stock split, existing shares are divided into smaller denominations, increasing the number of shares held by investors in proportion to the split ratio (e.g., 4-for-1 split quadruples the shares held).
The passage clearly states that a stock split increases the number of shares outstanding in proportion to the split ratio (e.g., 2-for-1, 4-for-1). Option (B) is a trap — it says "double," which is only true for a 2-for-1 split, not all splits. Option (C) is the correct general answer. Note: the value of holdings remains unchanged after a split; only the number of shares increases proportionately.