Astudent infected by a common cold virus ran a low-grade fever. after a few days, the student’s temperature returned to normal and the student was free of cold symptoms. the fever served as
(1)an antigen in the circulatory system
(2)an immune response to a pathogen
(3)a biological catalyst
(4)a weakened pathogen

Ineed to know why d is the correct answer asap

Johnny rode his bike to a friend's house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was not able to play. what was his displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point

What are characteristics of minerals? select 3 choices