In a long bone, the osteons are:
a. lined up in the same direction as the diaphysis of the bone
b. lined up perpendicular to the long axis of the bone, in the direction of perforating canals.
c. arranged in an irregular pattern
d. are separated by medullary spaces
e. are lacking in the diaphysis of the bone

B. lined up perpendicular to the long axis of the bone, in the direction of perforating canals.

Explanation:

Osteons are formations of concentric bone layers (lamellae) that tend to run parallel to the long axis of a bone. They sorround the Haversian canal, a canal that contains blood vessels that supply the osteocytes and are the structural unit of compact bone.

I hope you find this information useful and interesting! Good luck!

"d.) carbon dioxide and hydrogen sulfide"

multiply it by 5 in order for you to understand i cant give an exact answer.