Final answer:
Lifejackets for infants and smaller children (less than 50 pounds) should have a proper fit and provide adequate head support.
Step-by-step explanation:
Lifejackets for infants and smaller children (less than 50 pounds) should have a **proper fit** and provide **adequate head support**. Infants and small children have different body proportions and are more susceptible to drowning due to their size and weight. Therefore, it is important for lifejackets designed for them to have a secure fit to ensure they stay afloat. Additionally, these lifejackets should have a collar or head support to keep their head above water and prevent drowning.