Match each term with its most suitable description.
$$ \text {_____ carbon dioxide } \quad \quad\quad\quad\quad \text {a. contains triple bond } $$
$$ \text {_____ bicarbonate} \quad \quad\quad\quad\quad \text {b. nutrient taken up by plant roots} $$
$$ \text {_____ nitrate} \quad \quad\quad\quad\quad \text {c. marine carbon sources } $$
$$ \text {_____ nitrogen gas} \quad \quad\quad\quad\quad \text { d. greenhouse gas} $$