How do firms choose their overhead cost assignment? How do firms choose optimal cash strategy determined by critical production activities that create and capture values? What is the nature and function of expense assignment? What are reasons for expense indicators or cost drivers? What are some policy implications of the Activity Based Costing in formulating effective cost assignment and spending budget strategies? The response to single factor value is trend. The tendency is the selection bias produced by the stimulation of the organism on a single environmental factor, which is the directional response form of the organism to the external stimulus, including the two basic forms of orientation and avoidance. The tropism has the tendency of phototropism, thermal tendency, wetness, tendency, and oxygenicity. It has the avoidance of light, heat, moisture, anaerobic and so on. For example, the acidity of paramecium, the thermal tendency of bedbugs and the phototropism of insects. The trend is the common response of low biological cells, biological tissues and protozoa. Tropism is in a series of internal inductance organically combined in a certain direction, to form a structure of ordering, and external single environment factor to form a single reaction, the biological function between the body and the external environment on the coherent function, to accelerate the ordering of the body development. When this series of inductivity is combined in a positive way, the tendency is formed. When this series of induction is combined in reverse, it forms a negative trend - the avoidance. In summary, the trend is the most elementary preordinate response to the external things of single factor value. The accounting income maintains the financial capital preservation, namely, the monetary value that only requires the owner to invest is not eroded, the enterprise income exceeds the input value part is the accounting income. Accounting focuses on reporting financial results. The economic benefits insist on physical capital preservation, which can only be confirmed when the actual production capacity of the owner is saved. It is believed that only by maintaining the actual production capacity of the enterprise can the enterprise reproduce smoothly. Physical capital preservation is more meaningful than the income of financial capital preservation, but it is difficult to measure. Stopping trading is an important part of the plan.