Final answer:
The most effective way of teaching word meanings to preschoolers is by providing a variety of concrete examples, as it allows children to understand the words in different contexts and enriches their cognitive development.
Step-by-step explanation:
Among the options provided, b) Providing a variety of concrete examples is the most effective teacher action for fostering a greater depth of preschoolers' comprehension of word meanings. When preschool-age children are exposed to diverse examples, they are better able to understand the nuances and contexts in which words can be used, which enhances their cognitive development. Using concrete examples, children can relate new vocabulary to things they have seen, heard, or experienced, which makes the word meaning more memorable and understanding more robust.
This approach is supported by education experts who emphasize the importance of rich and meaningful interactions to promote language development. By engaging preschoolers in conversations and activities that utilize new vocabulary in various situations, children can build a deeper understanding of word meanings that goes beyond rote memorization or limited, isolated usage.