which of the following statements is/are true with respect to the scientific theory . 1 theories are accepted expectations for how the world works. 2. the theory of evolution is considered the unifying concept in biology 3.theories can help scientists generate new testable hypothesis .4. thoeries are supported by many observations and expierments

"d.) carbon dioxide and hydrogen sulfide"

b is the correct answer

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)]