List the two main sources of renewable energy used in the United States.

because the light is a great source of energy for the plants to survive. (i hope this )

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]

if you listed your answers right then i believe your answer is b.