All living things are composed of one or more .
A. organs
B. cells

Providing immunity by injecting the body with a weakened form a pathogen is known as

Select the situation bellow that would produce a total displacement of zero. a. a trip to the moon and then to mars b. a horse galloping from one end of a field to another c. the criss-crossing path of a bug as it flies from flower to flower d.a round-trip ride to school and back

Describe two recent or ongoing space missions.