To investigate all these subareas is neither advisable nor feasible. Select only those subareas that would be possible
for you to study within the constraints of time, finance and expertise at your disposal. One way to select
your subarea is to start with a process of elimination: delete those areas you are not very interested in. Towards
the end it may become difficult but you need to keep eliminating until you have selected a subarea(s) that can
be managed within your constraints. Even one subarea can provide you with a valid and exhaustive study.