As per given by the question,
There are given that angle XBY is 70 degree and ray BA bisects.
Now,
According to the properties of the bisect,
A line that splits an angle into two angles.
Then the bisects means to divide into equal part.
Then,
Angle XBY is given that 70 degree.
So,
The angle XBA is equal to the half of the angle XBY, that means half of bisects angle.
The angle XBA is 35 degree.
Hence, the option B is correct.