Comprehensive and Detailed Explanation:

This question refers to Gagné's Nine Events of Instruction, a model for designing effective learning activities. One of the steps in this model is to activate learners' prior knowledge, which serves as a foundation for new learning. Here's why C is the best answer:

1. Activating Prior Knowledge in Gagné’s Model:

In Gagné’s Nine Events of Instruction, reminding learners of related knowledge or skills is part of the event “Stimulating recall of prior learning.”

This step is crucial as it helps learners connect what they already know to the new content, making the learning process smoother and more meaningful.

2. Why Option C is Correct:

Reminding learners of related knowledge or skills increases their understanding of what the new learning will enable them to do by providing context and relevance.

It helps bridge the gap between existing knowledge and new concepts, allowing learners to see the practical value and application of the new material.

3. Analysis of Other Options:

Option A: Enables learners to understand how they learn.

While activating prior knowledge might give some insight into learning processes, this is not the primary reason for reminding learners of what they already know.

Option B: Helps learners plan to use immediately what they learn.

Planning for immediate application is a valid outcome of effective learning but not the primary reason for recalling prior knowledge.

Option D: Reduces learners’ concerns about new learning.

While recalling prior knowledge may ease anxiety, this is not the main purpose in Gagné’s model. The focus is on understanding and connecting prior knowledge to new concepts.

4. Practical Example:

If a learner is being introduced to a new software tool, reminding them of their previous experience with similar tools helps them relate to the new content and understand how the new tool will expand their capabilities.

5. Reference to Gagné’s Model:

Event 3: Stimulate Recall of Prior Learning

This step facilitates the integration of prior knowledge with new material, which enhances comprehension and retention.