When a substance was tested on both red and blue litmus paper, neither the red or blue litmus paper changed colors. Therefore, the
substance tested was most likely:

a. neutral
b. a base
c. an acid
d. invisible

A.neutral

Explanation:

When blue litmus paper is placed in a substance that is acidic, it will turn to red. However, if placed in a substance that is basic or neutral, it will remain blue.When red litmus paper is placed into a basic substance, it will turn blue. If it comes in contact with an acidic or neutral substance, it will remain red.

air

in a tire you fill a tire with air

then a couple days later you check the air pressure in the tire

hope this mark me brainliest

it's c (engineer's do their work with mechanical stuff not on any living being)