Explanation:

- Ponder: To think about something carefully or to consider deeply.

- Option 1: Terminate: Means to bring something to an end or to conclude.

- Option 2: Celebrate: To acknowledge a significant event with enjoyable activities or ceremonies.

- Option 3: Agitate: To stir or disturb something or to cause anxiety.

- Option 4: Meditate: Involves thinking deeply, often in a calm and focused manner, about a particular topic or engaging in mental exercise for relaxation.

- Correct Answer: Option 4: Meditate

Both "ponder" and "meditate" share meanings related to deep thinking or contemplation.