Final answer:
The change that is unintentional and results from informal organizing is known as accidental change, which is influenced by various external factors and arises organically within a society.
Step-by-step explanation:
The type of change that is unintentional and is usually the result of informal organizing is d. Accidental. Accidental change often occurs without a deliberate plan or direction and can be influenced by external factors such as technological innovations, environmental shifts, and population dynamics. These unintentional changes can result in modernization or other alterations to social structures and institutions. Unlike planned or revolutionary movements, accidental changes are not orchestrated by organized groups seeking specific goals. They arise organically from the interplay of various elements within a society, often without immediate recognition.