Step 1: Understanding the Question:
This question tests knowledge of alley cropping design.
Step 2: Detailed Explanation:
The ideal ratio of tree to crop in alley cropping is 1:10.
This means one tree row for every ten crop rows.
This ratio minimizes competition and maximizes productivity.
2:10 (B): Too many trees.
3:10 (C): Too many trees.
4:10 (D): Too many trees.
Thus, the correct answer is 1:10.
Step 3: Final Answer:
Thus, the ideal ratio is 1:10, which corresponds to option (A).
[0.5cm]