I will try to explain the process I used to answer this question.

Premise - A recent survey found that more computers than copies of computer programs were purchased by Germans last year.

Conclusion - The best interpretation of this finding is that the practice of illegally duplicating commercial computer programs is widespread among Germans.

As we can see, argument is weak and can easily be attacked.

A: In my personal opinion, this is irrelevant to the argument. We are not talking about users who write then own programs. Also, we cannot say that writing your own programs is the only way to use legitimate software.

B: This option seems out of scope to me. We are talking about commercial programs and not non-commercial programs

C: I think this statement counter the premise and not the conclusion. Let us say we found that there were 1000 computers purchased and only 500 commercial programs purchased. I could be possible that out of 1000 computers, 500 computers are bought in another country. And rest 500 computers are all using legitimate commercial program. That means there is an alternate explanation for survey findings

D: We do not know whether these computer programs are purchased or duplicated.

E: This one was tricky in my opinion. If duplicate programs are counted as legal programs, then I feel this statement supports premise, and in a way helps conclusion

I sincerely feel there should be more to explanations than I provided here.

Ameya

(A) Few German computer users write their own computer programs.
This offers an objection although not much because of usage of FEW. FEW means no one. So this may be supporting the argument.
(B) There are few free noncommercial computer programs available in Germany.
Again same as above A FEW would have helped. Non commercial programs do not add to piracy.
(C) Some Germans purchase computers outside of Germany for use in Germany, and such purchases were counted in the survey.
The argument is about piracy. Doesn't matter much about the purchase. IF computers are used with illegal software IN GERMANY, IT is still piracy
(D) The typical German computer user has several commercially written computer programs on his or her computer.
This adds to the argument. IF there are several commercial applications and if statistics say that only less number are acutally purchased, there is high chance that many are illegaly copied.

(E) Many Germans legally make duplicates of commercial computer programs, but such duplicates were counted as purchased copies in the survey.
Legal duplicates same as purchased copies. Even if we reduce the number of legal duplicates the purchase copies number still reduces. Ignore the CR.