Final answer:
Corn, beans, and squash are three ecologically symbiotic staple crops commonly planted together in a technique called intercropping. When planted together, these crops yield higher amounts of calories and protein compared to when they are cultivated alone.
Step-by-step explanation:
The three ecologically symbiotic staple crops are corn, beans, and squash. These crops are commonly planted together in a technique known as intercropping, with each crop benefiting the growth of the others. For example, corn provides stalks for bean plants to climb, beans contribute nitrogen to the soil, and squash plants block weeds and protect the root systems of all three crops. When planted together, the three crops yield as much as two to four times the amount of total calories and protein than they would if cultivated alone.