The puzzle is as follows:
How many straight lines do you need to draw the least possible to join all the smiling toasters if you should not raise the pen or go over any line already drawn? Remember that it is allowed to cross.
The alternatives given are as follows:
How should this puzzle be approached? I'm getting 7 lines, however, I think there are different ways. Is there a way to minimize the trials?
I found this riddle in a book Logical Challenges from 2000's. It seems to be an adaptation from a reprinted copy of Martin Gardner's Puzzle's book from 1970s.
Because this puzzle has a drawing it would help if answers also included drawings so I could properly visualize the lines and understand why they are there.