Final answer:
Based on the developmental milestones of infants, the appropriate verb to complete the sentence 'the baby can _ across the room' is 'crawl.'
Step-by-step explanation:
The sentence you have provided "the baby can _ across the room" seems to describe an action that the baby is capable of doing. Considering the development stages of an infant according to the age-related milestones, a suitable verb to fill in the blank could be "crawl." Infants around ten months old are often able to crawl as part of their developmental progress. This is further supported by descriptions of infants showing signs of crawling around this age and starting to engage with their environment, such as transferring objects from hand to hand, sitting unsupported, and showing curiosity in their surroundings.