Final answer:
In BLS, an infant is defined as a child under one year old. Different age groups, such as children ages 0 to 2.5 and other brackets, require specific resuscitation techniques.
Step-by-step explanation:
For Basic Life Support (BLS) purposes, the age considered an infant is under one year (a). This categorization is important as it informs the appropriate procedures and techniques used during resuscitation efforts. Age-specific guidelines are critical in administering BLS correctly, and these guidelines differentiate between infants, children ages 0 to 2.5, children ages 2.5 to 6, children ages 6-13, and adolescents ages 13-20, with each group requiring different approaches to BLS.