The First line of defense in the immune system A( block pathogens from entering block
B( KIll infected cells
C( Send signals to increase immune cell formation
D( kill the pathogen

The serengeti plains are part of the african savanna ecosystem and are home to a variety of different species of plants and animals. the serengeti plains experience a seven-month period of seasonal drought each year, during which the ecosystem receives only four inches of rain and the availability of some resources becomes very scarce. which type of limiting factors does the seasonal drought in the serengeti plains affect?