All four options listed are products of volcanic eruptions, which is significant in understanding various geological and environmental processes. Pyroclastic debris and ash and dust are directly ejected from an erupting volcano, contributing to volcanic landforms and influencing local geology. Additionally, nitrogen and sulfur compounds are emitted during eruptions, affecting atmospheric chemistry and climate patterns, such as acid rain and the greenhouse effect, highlighting the intricate connections between volcanic activity and global environmental systems — a critical consideration in UPSC Prelims for topics like natural disasters, ecology, and climate change.