Identifying the One-Word Stage in Language Development

Language development is an essential area of study in cognitive psychology, particularly in understanding how children learn to communicate. One of the key components of language development is the sequence of stages that children typically go through as they acquire language skills. This process includes babbling, single words, two-word phrases, and eventually more complex sentences. These stages have been extensively researched, and understanding them can help educators and parents support children's language learning.

Which of the following stages of language development is typically characterized by a child’s use of single words to express whole ideas, often referred to as 'holophrastic speech'?