Final answer:
A firm's selection method for projects should always be objective to ensure decisions are based on factual analysis rather than subjective opinions.
Step-by-step explanation:
The question pertains to the selection methods that firms should consistently use, irrespective of the specific project or investment. Regarding the selection method a firm uses, the correct answer is that it should always be objective in their selection method, which corresponds to option C in the question. Predicting the exact revenue (A) or project success (B) is not always possible due to inherent uncertainties and external factors that can affect outcomes. While weighted scoring techniques (D) can be useful, they are not required universally. Objectivity ensures that decisions are made based on data and factual analysis rather than subjective opinions, which is crucial for business decision-making and investment selections.