Correct Answer: blissful

Solution : The correct choice is the third option.

Explanation: "Blissful" means extremely happy or joyful, capturing the essence of a positive and serene environment suggested by the presence of green, content plants. This term not only aligns well with the context of the sentence but also brings out the emotional aspect of the scene, emphasising the happiness associated with the vibrant and flourishing plants. The word "blissful" conveys a sense of utter joy and contentment, making it the ideal synonym to enhance the positive tone of the sentence.

So, the correct sentence would be: "You look around and you see green, blissful plants".