In the diagram, structure D corresponds to:

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)]

in the year 2850, humans successfully colonized mars. the martian modules that were constructed could hold only a small population of people. it is now a century later, and the population on mars has grown to 600 people. of the current mars population, 45 people express the recessive phenotype for phenylketon- uria (pku) syndrome (pp genotype).

explanation: