A potential problem related to the physical installation of the Iris Scanner in regards to the usage of the iris pattern within a biometric system is: 在一个生物系统内的虹膜图案的使用方面涉及到的虹膜扫描仪物理安装的一个潜在问题是：（）

• A、the optical unit must be positioned so that the sun does not shine into the aperture.光学设备必须被定位以便使太阳照进光圈
• B、there is are latively high rate of false accepts.有一个相对较高的错误接受率。
• C、the iris pattern changes as a person grows older.虹膜图案随着一个人年龄的增长而变化。
• D、concern that the laser beam may cause eye damage.关注激光束可能会导致眼睛损伤。