DNA is copied during replication.
Lead emission since early 1980s have DECREASE DUE TO LEAD FREE GASOLINE.
Lead is a natural occurring element that is found in small quantity in rocks and soils. Lead emission is an important environmental health issue because a very small quantity of lead can cause adverse effects on the nervous system of unborn babies and young children. Because of this, the government took all necessary measures to ensure that its emission was drastically reduced.
B is your answer. God Bless hope this helps
They contain symbiotic bacteria called rhizobia within nodules in their root systems, producing nitrogen compounds that help the plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released, making it available to other plants; this helps to fertilize the soil.