(A)

No. 11

1 Our brains do not age in the same way as our bodies do.

2 Electrical stimulation may cause serious mental issues.

3 Learning is not connected to other brain functions.

4 Synchronizing brain waves improves memory function.

No. 12

1 It has potential uses beyond improving memory and learning.

2 It has helped to identify previously unknown conditions.

3 It has demonstrated long-term effectiveness.

4 It has proved unsuitable for treating brain disorders.