Which of the following is the best description of the "identifying tasks" issue in threading?

When it's hard to create parallelism due to serial dependencies within the program.

When it's hard to determine how to break a problem into smaller tasks

When it's hard to fix a program because it uses multi$-$threading

When it's hard to identify data needed by a thread and split it from the whole

When it's hard to make sure each thread gets the same amount of work to do