How are red blood cells able to move through narrow vessels to carry oxygen throughout a multicellular organism?

1. They are small because they lack a nucleus.
2. They are long and thin with a tail-like end.
3. They are small because their organelles are smaller than those of other cells.
4. They are flexible because they lack a plasma membrane.

1. They are small because they lack a nucleus.

3. They are small because their organelles are smaller than those of other cells.