I think the answer is D Ellipitical galaxy
Here is a link that can help you.
http://study.com/academy/lesson/what-is-an-organ-system-definition-pictures-quiz.html
~Hello there!
Your question: What substance is considered a building block for all living things?
Your answer: Carbon is the substance that is considered s building block for all living things.
Any questions ^?
Happy Studying!
<span>The cells of plants
and animals are similar expect for a few different structures like the shape of
the cells and cell wall. They differ in cell shape since animal cells are rounded
and it has irregular shape while plant cells have fixed shape which is
rectangular. Another structure is a cell wall. Animal cells don’t have cell wall
while plant cells have. Plant cell wall is a structure surrounding the cell
that provides a number of functions such as strength to support the plant, Flexibility,
Water-proofing, Barrier to pests, Protection against environmental stress, signaling
and sensing. </span>
