Which action is indicative of suspicious observation techniques?

The correct choice reflects a methodical approach to surveillance, which is central to the concept of suspicious observation techniques. Utilizing binoculars allows an observer to keep a discreet distance while closely monitoring a subject without drawing attention. Taking notes during this observation enhances the effectiveness by enabling the observer to document specific behaviors, patterns, or interactions that might warrant further investigation. This embodies the essence of gathering intelligence in a structured manner.

While the use of drones for aerial surveillance is a modern and effective tool, it may not always be perceived as discreet, which is a crucial element of suspicious observation techniques. Similarly, using a smartphone for pictures or requesting information from bystanders may not align with the goals of secretly gathering information without alerting the subjects to the scrutiny they are under. These methods involve a higher degree of interaction or visibility that can compromise the observational act's clandestine nature.