Final answer:
Opinions cannot be used as a reason in a two column proof because they are based on personal beliefs or preferences and do not provide objective evidence to support a logical deduction. Therefore, the correct answer is opinions (option d).
Step-by-step explanation:
In a two column proof, the reasons used to justify each step must be based on factual information and logical deductions.
Out of the given options, opinions cannot be used as a reason in a two column proof because they are based on personal beliefs or preferences and do not provide objective evidence to support a logical deduction.
Therefore, the correct answer is opinions (option d).