Final answer:
Baby Kenzie, who has just begun sleeping more at night and is awake more during the day, is most likely 3 months old. This is deduced from typical infant sleep patterns and developmental milestones.
Step-by-step explanation:
When considering if Baby Kenzie, who has just begun sleeping more at night and staying awake more during the day, is most likely 3 months old, 1 month old, 6 months old, or 1 year old, we can use the typical developmental milestones to deduce the answer. Infants generally start to show more regular sleep patterns and stay awake longer during the day as they grow out of the newborn stage. By 6 weeks, babies typically begin to smile and make vocal sounds, and by 4 months, they can hold their head steady, follow objects with their eyes and start to make vowel sounds and laugh. At 6 months, babies are babbling and starting to sit and crawl. Teeth may start to come in and they begin showing anxiety towards strangers. By the end of the first year, babies are usually walking and talking to some extent, and spending about as much time awake as asleep.
Considering these milestones, Baby Kenzie is developing sleep patterns consistent with a baby who is past the early stages where infants typically sleep longer spans during the day. Since Kenzie is beginning to have longer awake periods during the day and sleep more at night, the correct answer is A. 3 months.