Describe real life examples of the results of scientific investigation

-- We know that the Earth is a spinning globe.

-- We know what the weather will be like in your town tomorrow.

-- We know the distance from us to the Sun and the Moon.

-- Best of all:  Your doctor can give you shots so you won't get flu,
chicken pox, measles, mumps, whooping cough, tetanus, diphtheria,
smallpox, or polio. 

Almost EVERY kid used to get chicken pox, measles, and mumps
when I was in school, and thousands of kids used to die every year
from diphtheria and polio.  And now, you probably never heard of
most of these.

Letter a, because when there are unlike charges they will always attract to each other.