Espionage refers to the practice of

Espionage is defined as the practice of using spies or covert methods to gather secret or confidential information, typically related to national security or trade secrets. This involves stealthy and often illegal actions to obtain sensitive information from individuals, organizations, or nations. The choice that accurately captures the essence of espionage highlights the use of spies to obtain trade secrets, which is a common motivation behind espionage activities, particularly in competitive business environments or international relations.

The other options refer to different types of unethical or illegal behavior but do not encapsulate the primary definition of espionage. For instance, stealing financial information from competitors may involve corporate theft, but it doesn't necessarily involve the spy or covert element central to espionage. Engaging in corporate sabotage implies actions intended to harm a competitor’s operations rather than gathering information. Conducting unauthorized inspections might relate to an invasion of privacy or breaches of trust but lacks the secretive methodology associated with espionage. Thus, the choice correctly identifies the specific practice that defines espionage in its truest form.