Step 1: Understand what is asked.
We must read the chart and decide which company, A or B, has the higher profit growth rate over the years shown.
Step 2: Recall what profit means here.
Profit for each year is revenue minus cost, so we look at the gap between the revenue bar and the cost bar for each company.
Step 3: Track Company A.
Follow Company A's revenue-cost gap from the earliest year to the latest; the gap widens only modestly, showing a gentler rise in profit.
Step 4: Track Company B.
For Company B, the revenue bar climbs much faster than its cost bar, so the profit gap expands more steeply year on year.
Step 5: Compare the growth rates.
A steeper widening of the profit gap means a higher growth rate, and Company B shows the steeper trend.
Step 6: Conclude.
Therefore Company B has the higher profit growth rate.
\[ \boxed{\text{Company B}} \]