Answer:
The correct answer is: Morphology.
Step-by-step explanation:
Morphology can be understood as the study of the structure of an organism and its specific features and characteristics.
Morphology can be associated with the outside appearance of the individual, such as physical characteristics; shape, color, etc.
A person's smile, gestures, and the shape of their lips and their eyes are structural characteristics and they are part of the individuals' morphology.
In this particular case, Coach Parlier knew that Felicia's smile was not sincere because she was smiling with her mouth but not "With her eyes".
The feature that allowed the coach to determine this was: a) Morphology.