The reason why he could not do the work was because he had to attend to his mother who was ill.

hy he could not do the work was since

or which he could not do the work was because

hy he could not do the work was that

The reason why he could not do the work was because he had to attend t

1.	The reason why he could not do the work was because he had to attend to his mother who was ill.
A.	hy he could not do the work was since
B.	or which he could not do the work was because
C.	hy he could not do the work was that
D.	o improvement
Answer» D. o improvement