Certified Arborist Practice Exam 2025 – Comprehensive All-in-One Guide to Master Your Certification!

Elements like copper, chlorine, and boron are considered micronutrients. Micronutrients are essential elements that plants require in small quantities for their growth and development. These elements play crucial roles in various physiological processes within the plant, despite being needed in smaller amounts compared to macronutrients. Therefore, option B is the correct answer as it accurately identifies these elements as micronutrients.

The other options are not directly related to elements like copper, chlorine, and boron. Option A mentions defense and pH, which are important factors for plant health but not specifically related to these micronutrients. Option C refers to hardiness, which is more related to the plant's ability to withstand harsh environmental conditions. Option D lists characteristics such as bark texture, flowers, fruit, smell, and color, which are attributes of plants but do not specifically address the elements mentioned in the question.