Final answer:
Physical-asset specificity is the specialized investment type where job skills are not transferable to other employers, leading to economic dependency between the employer and employee (D).
Step-by-step explanation:
The type of specialized investment where job skills are not transferable to other employers is known as physical-asset specificity.
This term describes a situation where the skills and knowledge, or human capital, that workers acquire are so specialized to a particular company's operations that they cannot be easily applied to a position at a different company. This concept is commonly discussed in relation to transaction cost economics, where the investment in such specific skills can lead to a form of economic dependency between employers and employees.