The correct answer is E because Scrum depends on transparency, collaboration, and collective accountability.
If a Developer raises concerns about data security, the Scrum Master should encourage that concern to be brought to the Scrum Team as soon as possible so it can be openly inspected and addressed. Security is a serious product quality concern, and in Scrum, important issues should not remain private between two people when they affect the whole team's work and the quality of the Increment.
Option A may sound reasonable, but the Scrum Master should not unilaterally add security to the Definition of Done. The Definition of Done is created and evolved appropriately through the Scrum Team's work and organizational standards. Option B is too directive and bypasses team inspection and collaboration. Option C could eventually happen, but immediately creating a Product Backlog item does not address the need for transparency within the Scrum Team. Option D is incorrect because Scrum does not rely on a separate tester role to own quality concerns.
The Scrum Master should help the team surface the issue quickly so they can determine the right action together.