A researcher wants to know whether babies born into homes with older siblings develop speech skills earlier than babies who are born as only children

They need to try 5 groups children who are spoken to, children who have speech therapy and children that have two adults in the house, children who watch interactive TV as toddler and children who have all siblings at home 50% at least during baby feed, play, care and coordinate checks/ routines.

Step-by-step explanation:

Just label as is D and S its easy it literally cant be explained.