Medicine is: -a chemical substance used to treat, prevent, or diagnose a disease -a chemical substance that alters one or more functions of the body -the promotion of the health of an entire community by controlling the spread of disease -the art and science of treating and preventing disease

Which of the following represents a difference between viruses and viroids? a) viruses infect many types of cells, whereas viroids infect only prokaryotic cells.b) viruses have capsids composed of protein, whereas viroids have no capsids.c) viruses have genomes composed of rna, whereas viroids have genomes composed of dna.d) viruses cannot pass through plasmodesmata, whereas viroids can.