Final answer:
Vinegar is the best option for removing mineral buildup on a steam table, as its acetic acid content effectively dissolves inorganic deposits.
Step-by-step explanation:
The cleaning agent that would best remove mineral buildup on a steam table is vinegar. Vinegar, which is a dilute form of acetic acid, is effective in dissolving mineral deposits such as lime scale. These deposits are typically inorganic and acidic cleaning agents, like vinegar, are recommended for their removal. In comparison, bleach and ammonia are alkaline cleaning agents and are better suited for dissolving organic matter like fats and proteins. While lemon juice is also acidic, it is not as widely recommended for cleaning mineral deposits as vinegar. For mineral buildup, vinegar's acid-base property makes it the most suitable choice among the listed options to dissolve and remove such deposits, ensuring the steam table functions efficiently.