Question

How are red blood cells able to move through narrow vessels to carry oxygen throughout a multicellular organism? (1 point)
Responses

They are long and thin with a tail-like end.
They are long and thin with a tail-like end.

They are small because they lack a nucleus.
They are small because they lack a nucleus.

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

They are flexible because they lack a plasma membrane.

Answer 1

The correct response is:

**They are small because they lack a nucleus.**

Red blood cells (RBCs) are unique in that they are biconcave disc-shaped and lack a nucleus, which allows them to be smaller and more flexible. This flexibility enables them to squeeze through narrow capillaries and effectively transport oxygen throughout the body.