The answer is: (2) a dead or weakened form of the pathogen
The chicken pox vaccine (a.k.a. Varicella vaccine) is a live attenuated vaccine. Attenuated means weakened. It is attenuated so that it doesn't cause the disease in the person.
The first answer is wrong because 1) live vaccines are attenuated, not left in the original form 2) Giving large amounts of virus is resisted. Research tests are done to figure out how little virus can be given to the patient to induce a proper immune response without any side effects.
