In the early days of life on earth, plants were exposed to extremely high doses of ultraviolet radiation. constant uv exposure resulted in some land plants developing narrow leaves with thick, waxy cuticles. over many, many generations, these narrow leaves evolved into needles. plant needles are probably initially the result of a) adaptations for survival that some plants developed due to high temperatures on earth. b) somatic mutations that made some leaves thick and waxy, while other leaves did not change. c) neutral mutations to leaf tissue that would neither nor harm the plants living in such a harsh environment. d) a beneficial mutation that increased survival of certain plants that reproduced and passed the mutated gene to offspring.