Final answer:
Sliced bananas cut vertically are an appropriate finger food for a 7-month-old because they are soft and can be easily grasped by little fingers. Other items like popcorn, hot dog pieces, and whole grapes are choking hazards and not suitable.
Step-by-step explanation:
When introducing finger foods to a 7-month-old baby, it is critical to ensure that the foods are safe and age-appropriate. The suitable option from the list provided would be B. Sliced bananas cut vertically. Bananas are soft and easy for a baby to mash with their gums, and when cut into manageable strips, they are easy for little fingers to grasp and self-feed. On the other hand, options such as popcorn, hot dog pieces, and whole grapes pose choking hazards due to either their size or texture and should not be given to infants. Safe finger foods for this age group also include well-cooked vegetables like green beans and soft fruits like avocados, cut into appropriate sizes.