B. Add each Send Email activity to different steps in an automation.

Explanation:
To ensure that each email is fully sent before the next one begins sending in Automation Studio, you should add each Send Email activity to different steps in the automation. This way, each email send will be scheduled sequentially, ensuring that the next email won't begin sending until the previous one has completed its sending process.

Option A, adding each Send Email activity to a single step, would send all emails simultaneously, potentially causing overlaps or concurrency issues.

Option C, including a Verification activity between each step, wouldn't necessarily control the sequential sending of emails. Verification activities are typically used to validate data or conditions and are not directly related to controlling the timing of email sends.

Therefore, option B is the correct choice to ensure that each email is fully sent before the next one begins sending in Automation Studio.

correct answer is B

If each Send Email activity is added to a single step, all three will run simultaneously. So, the correct answer will be B.