Which of the following is an example of conventional breeding for disease resistance?
Inserting a gene from a virus into a plant's genome to confer disease resistance
Using chemicals to induce mutations in a plant's DNA to produce disease-resistant varieties
Cross-breeding two plants with different disease-resistant traits to produce offspring with improved disease resistance
Using CRISPR-Cas9 to edit a plant's genome to confer disease resistance
Cross-breeding two plants with different disease-resistant traits to produce offspring with improved disease resistance is an example of conventional breeding for disease resistance. This process involves selecting plants with desirable traits and crossing them to produce offspring with improved disease resistance. Hence, option 3 is the correct answer.