About how often does the sun have a pole reversal? A. every 22 years B. Every 250,000 years C. Every billion years D. Every 100 million years

You have been tasked with sorting the rock samples shown into three categories, with two rocks in each category. what attribute would you use to sort these rocks? which rocks would be in each category? rocks: obsidian, coquina limestone, granite, soapstone, pumice, and gneiss.