An observation can be acquired using the senses. In other words, observations can be seen, heard, tasted, smelled, and touched. It should be evident right there. It can also be made using tools that can measure the intensity of color, texture and any physical characteristics. These tools strengthen the credibility because human senses can be objective. But with these tools, it follows quality standards. However, an inference or a hypothesis is based on concept of causality. This is not an observation, but it came from one. Hence, from the choices, the answer is letter A.
