Scope consideration at time of making preferences . Good or bad ?

Many students particularly students of engineering are confused which field should they choose for their further studies.
At whatever point I am asked about this matter I essentially address choose the area of your interest. This answer seems, by all accounts, to be straightforward and one may suppose I am simply overlooking them . Give me a chance to clarify why I utilize this reply.

Two years back in 2011 when I joined Nust we were addressed by our head of Department. I would like to quote a couple of lines said by him:
" Students of undergraduate should not worry about the scope and job stuff at time of joining the institute. When you'll have a professional degree in your hands the market of entire world will be open up for you"

Why he asked not to worry about the scope and job?

You people will join the institute this year , complete BS in 4 years , some of you would go far MS and higher studies. So you will be doing the occupations after atleast 4 years and you are counseling about the employments 4 years prior. Does it make any sense to you ?
Acknowledge the illustration of Electrical Engineering. Three or Four years back there were a considerable measure of employments for electrical engineering and was stacked up first in this respect yet now the scenario is completely distinctive. Regarding occupations Civil , Mechanical, Software are above Electrical now. But this does not mean all of you should leave electrical and run after civil and software , although some of you would do this.

So on basis of which factor one should select his preferences? 

Preferences should be made on basis of your interest. In case your merit is low you cannot get in the desired discipline join the one which is most related to that discipline. There are number of fields these days. You can get an idea about the academic disciplines from the following link:
 https://en.wikipedia.org/wiki/List_of_academic_disciplines

How joining the field of your choice tends to work?

Provided that you select your zone of interest you will attempt to study more and more and this will help you gaining new aptitudes while in the event that you follow the fields with high justifies it is conceivable that you wont work that much productively in that field. To know in which field you can perform better counsel your school educators and your parents.

Choosing a field is a very important decision, think about it, use the web to know about different fields and then make the decision. Best of luck to all