Sentence Correction (SC) | Re: Thomas Eakins’ powerful style and his choices of subject—the advances

GMATNinja - i got the same query. I thought in his own time was the right idiom.

To his own time makes it sound like he was jerk to his own time
where as In his own time makes it sound like back in the day, in his time he was a jerk.

I ended up eliminating A n B based on that.