Mr. Roy sought mercy . . . . . . . . his father. A. with B. from C. along D. under

The correct answer is: from.

The word “from” is used to indicate the source of something. In this case, Mr. Roy is seeking mercy from his father.

The other options are incorrect because they do not indicate the source of something. The word “with” is used to indicate association or cooperation. The word “along” is used to indicate movement in the same direction. The word “under” is used to indicate a position below or beneath something.