Question about the usage of もの and こと in Shinkanzen Master N2 Grammar


This question is from one of the practice tests in the Shikanzen Master N2
Grammar.

> あの人が( ) 。遊んでばかりですよ。
>
> a) まじめなことですか
>
> b) まじめなものですか
>
> c) まじめなはずですか
>
> d) まじめというものですか

I answered `c` as my thought process was that it says something along the
lines of: `"Was that guy supposed to be serious? He is playing around all
day!"`. However, the correct answer is `b`. In the first place, I don't
understand what the meaning of the sentence is. Additionally, to solve this
question, the key seems to be the difference between `もの` and `こと`, but since
the meaning is not crystal clear to me, I went for the other option. I was
wondering why `b` is the correct answer and what the sentence actually means.




The key factor to understand here is the construction `ものですか`. As explained by
[this
post](https://japanese.stackexchange.com/questions/55568/%E3%82%82%E3%81%AE%E3%81%8B-%E3%81%9D%E3%82%93%E3%81%AA%E3%81%B0%E3%81%8B%E3%81%AA%E3%81%93%E3%81%A8%E3%81%8C%E3%81%82%E3%82%8B%E3%82%82%E3%81%AE%E3%81%8B-such-
a-stupid-thing-or-not-stupid-at-all), the nuance fits perfectly with the tone
of the sentence, therefore `b)`.

あの人が **まじめなものですか** 。遊んでばかりですよ。

When I post this question a month ago, I didn't check the meaning of `ものですか`
because it was presented in the book until a little bit later.

P.S Thanks to @Chocolate for the link.




The key factor to understand here is the construction `ものですか`. As explained by
[this
post](https://japanese.stackexchange.com/questions/55568/%E3%82%82%E3%81%AE%E3%81%8B-%E3%81%9D%E3%82%93%E3%81%AA%E3%81%B0%E3%81%8B%E3%81%AA%E3%81%93%E3%81%A8%E3%81%8C%E3%81%82%E3%82%8B%E3%82%82%E3%81%AE%E3%81%8B-such-
a-stupid-thing-or-not-stupid-at-all), the nuance fits perfectly with the tone
of the sentence, therefore `b)`.

あの人が **まじめなものですか** 。遊んでばかりですよ。

When I post this question a month ago, I didn't check the meaning of `ものですか`
because it was presented in the book until a little bit later.

P.S Thanks to @Chocolate for the link.

