First things first, concurrent programming is very different from parallel computing. Concurrent programming is a paradigm of software design and parallel computing deals with how processes are run in parallel.
"In programming, concurrency is the composition of independently executing processes, while parallelism is the simultaneous execution of (possibly related) computations. Concurrency is about dealing with lots of things at once. Parallelism is about doing lots of things at once" - Rob Pike
The bane of concurrent programming is shared mutability. Shared mutability of objects is the major reason for bottlenecks and slow code.
Here is a great talk that explains it very well
Your answer should be,
I will design in the application such that I will minimize shared mutability and try to give the example of the gopher burning books from the video above.