Final answer:
Firms choose private transportation for various reasons, but industry standards is not one of them.
Step-by-step explanation:
Firms choose private transportation for several reasons such as greater control, cost savings, and service quality. However, the option d) Industry standards is not a reason why firms would choose private transportation. Industry standards are guidelines or regulations that companies in a specific industry need to follow, and it does not play a role in the decision-making process for private transportation.