Tế bào limphôT có khả năng ra chất nào?

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

The response is the basis for vaccination. primary secondary tertiary none of the above

Individuals do not compete directly for resources, but are prey for the same predator