What are the differences between low pathogenic avian influenza (LPAI) viruses and highly pathogenic avian influenza (HPAI) viruses?
a. LPAI viruses are more contagious than HPAI viruses
b. HPAI viruses cause less severe disease in birds
c. HPAI viruses are more severe in their effects on poultry
d. LPAI viruses have a higher mortality rate in humans
