Final answer:
A constant playing of the radio is not helpful for language development in an infant classroom as it can create a noisy environment that overwhelms infants, hindering their ability to focus on language learning.
Step-by-step explanation:
One thing that would not be helpful for language development in an infant classroom is b. a constant playing of the radio. Activities that foster language acquisition include adults who speak face to face with babies, adults who speak the infant's home language, and soft music playing at nap time, which can be soothing but does not interfere with language learning. In contrast, a constant playing of the radio can overwhelm infants with stimuli, potentially making it difficult for them to focus on language learning cues and engage in the quiet observation needed to process and imitate language.