Step 1: Understanding language development in children.
Language development in infants follows a gradual process. Initially, babies communicate through crying and babbling before they begin to use recognizable words.
Step 2: Developmental milestones.
Most children begin to say their first meaningful word such as "mama" or "dada" around the age of one year. This stage is commonly referred to as the single-word stage in language development.
Step 3: Evaluating the options.
- (A) 12 months: Correct. Around one year of age, children usually start using single words to communicate.
- (B) 5 months: Incorrect. At this stage babies mainly babble but do not form meaningful words.
- (C) 8 months: Incorrect. Babies may produce sounds but meaningful single-word communication is uncommon.
- (D) 10 months: Incorrect. Some vocal imitation may occur but clear one-word communication generally appears closer to 12 months.
Step 4: Conclusion.
Therefore, children typically begin to use one meaningful word to communicate at about 12 months of age.
Final Answer:} 12 months.