Directions: In the following passage some words have been deleted. Read the passage carefully and select the most appropriate option to fill in each blank.

Trees are (1)________ best gift of nature for us. They make the environment beautiful and clean. Water and sunlight are very important to helping trees grow. Human beings get food from trees. Trees also give us wood and shade. Houses, chairs, and toys (2) ________ from wood we receive from trees. Trees can be called the best friends of mankind. Many animals get their food from leaves, vegetables, and fruits grown (3) ________ trees. They also live in the shadows of trees. We (4) ________ cutting trees to save nature. Children and adults need to plant more trees and teach each other to stop causing harm to (5) ________. One tree can save many lives.

Select the most appropriate option to fill in blank number 4.

The correct answer is should stop.

Step-by-step Explanation:

1. Understand the context of the sentence:
The passage emphasizes the immense value of trees to nature, human beings, and animals. The sentence reads: "We (4) ________ cutting trees to save nature." This sentence conveys a strong recommendation, moral duty, or necessity to preserve nature by discontinuing the practice of cutting down trees.

2. Analyze the grammatical rules:
- The modal verb "should" is used to express advice, duty, obligation, or recommendation. Modal auxiliary verbs are followed by the base/bare infinitive form of the verb (verb in present/root form, i.e., stop). Therefore, "should stop" is grammatically sound and fits the intended message.
- The option "may stopped" is grammatically incorrect because modal verbs like may must be followed by the base verb (stop), not the past participle form (stopped).
- The option "can stopped" is grammatically incorrect for the same reason (modal verb can followed by stopped instead of stop).
- The option "have stop" is grammatically incorrect because the auxiliary verb have requires the past participle form (stopped), i.e., have stopped.

3. Conclusion:
The phrase "should stop" is both grammatically correct and appropriate in meaning. Thus, the complete sentence is: "We should stop cutting trees to save nature."