The strategy of vaccination to fight diseases uses what type of immunity?
a. non-specific immunity
b. cell-mediated immunity
c. natural immunity
d. specific immunity
e. passive immunity

Passive immunity

Explanation:

The strategy of vaccination was a type of passive immunity. Passive immunity can be introduced artificially when antibodies are given as a medication to the non immune individual.

This is done in case of vaccination, attenuated form of bacteria is injected or orally given to the individual to evoke immune response when the body is exposed to the same bacteria again.

The attenuated form of bacteria evoke the immune system to produce memory cells which will kill the bacteria when it is encountered for the second time.

Object is moving away from observer.

Explanation:

If a force is applied to an object it starts moving. The object will move towards the observer, this is known as Doppler effect. It is when an observer or the thing under observation moves. There is change in its position due to a force exerted on it. The motion of the object also depends on the direction of force.