What properties of carbon explain carbon's ability to form different large and complex structures?

Solution:

Carbon has several allotropes, or different forms in which it can exist. These allotropes include graphite and diamond, which have very different properties. Despite carbon's ability to make 4 bonds which helps it in sharing with the other elements to form complex compounds. These properties of carbon shows the ability of the carbon that forms different and complex compound.

Thus the required answer is Carbon has b four valances in its outermost orbit which helps it to form more complex compounds .