Meaning: 'Reflexes' are automatic responses to stimuli, such as sucking or grasping, that infants are born with.

Wrong options:

• route: The word 'route' refers to a path or direction and does not relate to the involuntary actions of infants, making it contextually irrelevant.
• emotion: 'Emotion' pertains to feelings and does not describe the physical actions or responses of newborns, thus it does not fit the context.
• flexes: While 'flexes' could refer to bending movements, it is not a commonly used term in this context and does not encompass the range of involuntary actions like 'reflexes' does.

Correct answer: sensitive

Explanation: The word 'sensitive' appropriately describes newborns' heightened awareness and responsiveness to visual stimuli, fitting grammatically and contextually within the sentence structure.

Meaning: 'Sensitive' means having a heightened ability to perceive or respond to stimuli, which is applicable to how newborns react to visual patterns.

Wrong options:

• subjective: 'Subjective' refers to personal opinions or feelings, which does not apply to the objective observation of newborns' visual responses.
• fundamental: 'Fundamental' means basic or essential, but it does not convey the specific responsiveness to visual patterns that 'sensitive' does.
• objective: 'Objective' implies impartiality or lack of bias, which is not relevant in describing the innate reactions of infants to visual stimuli.

Correct answer: discriminate

Explanation: The term 'discriminate' fits grammatically as a verb that indicates the ability to recognize differences, aligning contextually with the developmental milestones of infants in recognizing faces.

Meaning: 'Discriminate' means to recognize or differentiate between things, which in this context refers to infants' ability to tell apart different faces.

Wrong options:

• disown: 'Disown' means to refuse to acknowledge or maintain a relationship with someone, which is not relevant to the context of recognizing faces.
• disorient: 'Disorient' means to confuse or make someone lose their sense of direction, which does not apply to the ability to recognize faces.
• disjoint: 'Disjoint' means to separate or disconnect, which does not fit the context of recognizing or differentiating between faces.

Correct answer: predilection

Explanation: The word 'predilection' fits grammatically as a noun that indicates a preference or liking, which is contextually appropriate when discussing infants' attraction to their mother's voice.

Meaning: 'Predilection' means a preference or special liking for something, in this case, the tones of their mother’s voice.

Wrong options:

• reflection: 'Reflection' refers to the throwing back of light or an image, which does not relate to the concept of preference in this context.
• flection: 'Flection' is a less common term that refers to bending or curvature, which does not apply to the context of preference for sounds.
• selection: 'Selection' implies the act of choosing, but it does not convey the idea of an inherent preference as effectively as 'predilection' does.