Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
|  | Organ/Plant structure |  | Input |  | Output |
| --- | --- | --- | --- | --- | --- |
| A(n) | brain | take(s) in | sensory information from sight, smell, taste, and touch | and gives off | signals that tell the body what to do |
| The | thyroid | take(s) in | iodine; tyrosine | and gives off | triiodothyronine (T3); thyroxine (T4); calcitonin |
| The | eyes | take(s) in | light | and gives off | signals that tell the brain what the eye has seen |
| The | lungs | take(s) in | oxygen | and gives off | carbon dioxide |
| The | heart | take(s) in | blood | and gives off | blood |
| The | liver | take(s) in | blood | and gives off | blood that is cleansed of toxins |
| The | pancreas | take(s) in | hormones; signals from the nervous system | and gives off | insulin; digestive enzymes |
| The | stomach | take(s) in | nutrients | and gives off | digested food |
| The | spleen | take(s) in | blood | and gives off | blood that is cleansed of toxins |
| The | kidney | take(s) in | blood | and gives off | red blood cells; opsonins; properdin; tuftsin |
| The | muscle | take(s) in | fats; carbohydrates | and gives off | ATP |
| The | colon | take(s) in | nutrients; water | and gives off | feces |
| The | esophagus | take(s) in | nutrients | and gives off | nutrients |
| The | veins | take(s) in | blood | and gives off | blood |
| The | arteries | take(s) in | blood | and gives off | blood |
| The | nerves | take(s) in | electrochemical nerve impulses | and gives off | electrochemical nerve impulses |
| The | small intestine | take(s) in | food | and gives off | digested food |
| The | gills | take(s) in | water; oxygen | and gives off | carbon dioxide |
| The | roots | take(s) in | water; nutrients | and gives off | water; nutrients |
| The | stem; stalk | take(s) in | water; nutrients | and gives off | water; nutrients |
| The | chloroplast | take(s) in | water; carbon dioxide; sunlight | and gives off | oxygen; ATP; NADPH |
| The | stomata | take(s) in | water; carbon dioxide; oxygen | and gives off | water; carbon dioxide; oxygen |
Question:
What do the gills give off after taking in oxygen from the water? Select the correct choice to answer the question or fill in the blank.
Choices:
(A) carbon dioxide
(B) calcitonin
(C) nutrients
(D) feces
Answer:
(A) carbon dioxide