Compact bone tissue is described as:

Compact bone tissue is characterized by its dense structure, which gives it strength and resilience, crucial for supporting the body's weight and facilitating movement. Under a microscope, compact bone displays a highly organized arrangement of osteons, or Haversian systems, which are cylindrical structures that appear as concentric circles. This organized layering is essential for efficient nutrient delivery and waste removal through the canal system within the bone. The dense nature of compact bone tissue contrasts with spongy bone, which is less dense and has a porous structure.

The other descriptions do not accurately represent compact bone. Thin and porous would describe spongy bone rather than compact bone. Flexible and rubber-like suggests characteristics more akin to cartilage than bone. Granular and opaque does not capture the structured appearance of compact bone under microscopic examination. Thus, the description of compact bone as thick and exhibiting many circles under a microscope aligns perfectly with its anatomical and functional characteristics.