Final answer:
Dermal tissue can form multiple layers in vitro by adopting behaviors similar to continuous cell cultures that exhibit anchorage-independent growth and lack contact inhibition. The answer is A.
Step-by-step explanation:
What allows dermal tissue to form multiple cell layers despite the inhibition of cell division in anchorage and density-dependent conditions is the behavior akin to that of continuous cell cultures, which unlike primary cultures, show anchorage-independent cell division and are notably unaffected by contact inhibition. The inherent attributes of continuous cell cultures, often arising from transformed cells or tumors, allow for sustained cell proliferation even after reaching a critical density.
Normal cells adhere to the culture dish's solid surface until they reach confluence, at which point contact inhibition normally ceases further division. Contrastingly, transformed cells forming a continuous cell line lack the ability to recognize confluence due to diminished cell communication mechanisms, such as gap junctions and adhesion molecules like cadherins and integrins, enabling them to grow in multiple layers.
Moreover, the difference in behavior between normal and cancerous cells in response to external events, such as the presence of growth-promoting hormones or the size of the cell, can illustrate alternative regulatory mechanisms which override the standard inhibition of cell proliferation.