It's true that the English 'to pose' can be used to translate the French 'poser', but only in the intransitive sense, so 'il pose' can be translated as 'he poses' or 'he is posing'. However, once a direct object is introduced, such as in 'il pose des roses', I don't believe that this translation can be used anymore - it becomes a bit of a false cognate then.
I'm under the impression that the translation 'to pose' can really only be used in the transitive form if the object is 'a question' or 'a problem'. If you really want to translate 'he poses the roses' into French (already quite a rare occurrence in English), I think you really need to say 'il fait poser les roses'.
I really hope this helps!
Another acceptable translation is "He puts down some roses." "He poses some roses" doesn't mean flower arranging in this particular instance, but simply putting some roses in a specific spot. The word implies a greater degree of precision than simply "putting" or "placing" them, though both work to translate this sentence.
Don't expect the sentences you come across on Duolingo to be useful things you hear everyday. It's the sentence structure and vocabulary that counts with Duo, rather than entire phrases.
As I said above, it is not anything that would be said in English. I flagged it more than once, but not enough of us "native English speakers" have flagged it yet. (This forum doesn't affect anything in the Duolingo phrase lexicon - it is just for us to share ideas with and learn from each other.)
Sorry, but that would be "Il euthanasie des roses".
A. He has a bunch of roses in his hand and he lays them down flat on a grave.
B. He is planting roses.
C He is arranging roses in a bouquet ( a bunch of flowers)
D. He is insulting the roses, presumably those of a neighbour. ( I have never seen such terrible roses. They look like weeds)
Could a French speaker please indicate A, B, C or D.
Is it possible that the sentence could refer to planting (= the ultimate "putting down" or "setting down", in the plant kingdom) as well as to the placing (on a table, on a tomb, etc.) of the full-grown blossoms?
If so, we'd want to translate "He sets out (botanical sense) some roses" or "He plants some roses."
Anybody know if this works?