Which tool has greatly reduced the number of people who have died from infectious diseases, disinfectants antiseptic, analgesics, antibiotic

for me i have felt invisible when i was clearly struggling,or,i made a great achievement ,and,nobody took to notice me either because they just didn't see it,or,people just turned their back on me.i can see a person being invisible by choice,or,without choice like i did.the people who are invisible by choice don't try to talk to people,don't try to make friends,and,keep to themselves.i haven't been one of those people so i couldn't give you a reason.

hope this and can i get bainliest my dude : d

answer: i would say the brain but it seem that you have a brain.