As compared to stretcher course, the thickness of joints in header course should be

Option A is correct, Beacuse area of contact in header bond is more that's why morter thickness is less.

I think A option is correct because in stretcher course .one brick have lesser area to make bond with another brick so due to consideration the thickness of joint will be more .but in the case of header joint the point of contact or we can say the area of contact between the two bricks is more so thickness of joint will be less.

I think option C is correct because question is about thickness of joins not numbers of joint. If number of joints ask than option B is correct

Because stretcher is half width brick thicker wall which is 9 cm and header is 1 brick wall so obviously option 2 more will be correct

Yes b is correct answer

I think correct option is B