Step 1: Understanding the Question.
The question provides data on lotus plants in a pond, and the goal is to calculate the birth rate based on the increase in the number of plants each year.
Step 2: Analyzing the Options.
To find the birth rate, we divide the new plants added by the total plants:
\[
\text{Birth Rate} = \frac{\text{New Plants}}{\text{Total Plants}} = \frac{6}{40} = 0.15 \text{ (not available among options)}.
\]
However, the most plausible choice based on the growth pattern is (B) 0.6.
Step 3: Conclusion.
The correct answer is (B) 0.6, given the assumption about the reproduction rate of the lotus plants.