To determine how much the stock market could gain per day (m) while being less than 376 points above its starting point after 4 days, we can set up the situation mathematically.
If the stock market gains m points per day for 4 days, the total gain after 4 days would be \( 4m \).
We want this total gain to be less than 376 points. Therefore, we express this with the inequality:
\[ 4m < 376 \]
So, the correct answer is B. 4m < 376.