Final answer:
The individuals mentioned in the options (Cicero, Cassius, Spartacus, Pliny the Elder) are known for their contributions to Roman politics, military, and literature, but none are historically recognized for being spies or for notable stealthy movement.
Step-by-step explanation:
The question seeks to identify a Roman figure known for espionage and quiet movement. However, none of the options provided, a) Cicero, b) Cassius, c) Spartacus, or d) Pliny the Elder, are historically recognized for being spies or particularly noted for their stealth. As a tutor, I must clarify that these individuals held other roles in Roman history:
- Cicero was a renowned orator and statesman.
- Cassius was a key figure in the assassination of Julius Caesar.
- Spartacus was a famous gladiator who led a major slave uprising.
- Pliny the Elder was a scholar and author, most known for his work 'Natural History'.
Therefore, the question may be based on a misconception, as the individuals mentioned are not famous for espionage activities in Roman times.