What is the outermost membrane surrounding the brain called?
pia mater
arachnoid mater
dura mater
alma mater

dura mater

Explanation:

The brain has three membranes between the bone, and the brain, the meninges: dura mater, arachnoid mater and pia mater.

Dura mater is the most external one, closest to the skull.

Arachnoid mater is the one in the middle. Looks like a spider-web, and that's why the name.

Pia mater is in touch with the brain and spinal cord, this is the thinner one.

humans are now responsible for causing changes in the environment that hurt animals and plant species. we take up more space on earth for our homes and cities. we pollute habitats. human activity often changes or destroys the habitats that plants and animals need to survive.

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)