What is the meaning of the word substantiate?

The term "substantiate" means to provide evidence or proof to support a claim or argument. In this context, confirming something entails validating or backing up assertions with facts or information. Therefore, when one substantiates a statement, they are essentially confirming its truthfulness or accuracy by presenting reliable evidence or reasoning.

The other options do not align with the definition of "substantiate." Inhibiting relates to hindering or restraining, assuming carries the meaning of taking something for granted without proof, and completing implies finishing something without any direct connection to proving or confirming evidence. Hence, confirming is the most fitting interpretation of "substantiate."