Concept:The problem tests the ability to calculate percentage remaining after a fractional part is removed.Explanation:One crate contains 30 eggs.The farmer sold 521 crates.Convert to improper fraction or decimal:521=5.5 crates.Total eggs sold =5.5×30=165 eggs.Total eggs produced =200 eggs.Eggs left =200−165=35 eggs.Now find the percentage left:20035×100=17.5%.Answer:The percentage of eggs left is 17.5%, which corresponds to option C.