Which is a better choice in case of a graduate admission? Which is a better choice in case of a PhD application and why:


Submitting a transcript which indicates an incomplete study (50/120 credits completed) and 5 dropped (not failed) courses. 


vs.


Concealing an incomplete study.


??

If #1 is a Hobson's choice, how can I explain that to satisfy the admission committe?
Concealing academic records is unethical and dangerous. It is not a good choice. Admissions committees sometimes discover such perfidy. And even when they don't, it does not build a strong foundation of ethics for your academic career.

As far as the uncompleted program goes, this depends on whether this is your only program, or a second program that you started and dropped out of.

Only program

Submitting a transcript which indicates an incomplete study (50/120 credits completed) and 5 dropped (not failed) courses will not get you into a graduate program. No program is accepting someone with less than half of their program completed. 


  If #1 is a Hobson's choice, how can I explain that to satisfy the admission committee?


There isn't a way. It's like asking "How can I get caught red handed on a video camera stealing bags of cash from a bank but convince the jury I'm innocent?" You can't. 

Second program

Honestly, unless there is some compelling reason ("My father died." "I was in the hospital with a broken back.") as to why you have so many dropped and uncompleted courses, there may not be a way you can just brush away your academic record into omission. There is not a great way to spin doctor this. 

I would just briefly explain that you started a program, and then explain why you did not complete it. If this uncompleted program is in the field you are applying for, this becomes a lot harder. You would then need to provide a compelling reason as to why you think this go-around will be more successful.