An important part of topsoil is
loam
permafrost
growing plant roots
decayed organic matter

decayed organic matter

Explanation:

Decaying organic matter is an important part of topsoil found worldwide.

Incorrect answers (with explanation):

Loam is a type of soil, not a part of topsoil.

Permafrost is only found in arctic regions, and is frozen ground, not a part of the soil.

Plant roots grow into topsoil, but are not a part of the soil itself.

I hope this helps!

brain development. a child's brain undergoes an amazing period of development from birth to three—producing more than a million neural connections each second. the development of the brain is influenced by many factors, including a child's relationships, experiences and environment.

explanation: