Final answer:
In physics, 'At' represents the time interval over which an event occurs, as opposed to a single instant 't'. Both examples given, a person standing and a car accelerating, involve changes over a time interval, indicating option C as the correct answer.
Step-by-step explanation:
The question appears to be related to the concept of motion in physics, particularly the notation used to represent the concept of time. The symbol 'At' is often used in physics to denote the time interval or the time taken for an event to occur, as opposed to a single instant in time which is represented by the symbol 't'. For example, if we want to discuss a car accelerating within a specific period, we may refer to the time interval 'At' which might cover the first 5 seconds of the car's motion.
When considering the examples provided - a person standing up from a seated position and a car accelerating while driving - both these situations involve a change over a period of time, and therefore the correct answer would be option C, which stands for 'both of the above'.