An example of a conjunction target would be:

The correct answer is that a yellow circle among green squares represents a conjunction target because it combines two features to identify a specific target object distinctly. In this case, the target has a unique combination of color (yellow) and shape (circle), distinguishing it from other objects present (green squares).

Conjunction targets are particularly significant in studies of visual attention and perception, as they require the observer to simultaneously attend to multiple attributes to identify the target successfully. The presence of both the specific color and shape makes it necessary for the observer to engage in a conjunction search, which typically requires more cognitive resources compared to identifying single-feature targets.

In contrast, the other options either present single-feature targets or combinations that do not showcase the necessary distinction of color and shape combination that characterizes conjunction targets. This illustrates the importance of understanding how multiple features can influence the perception and processing of visual information in cognitive psychology.