The correct answer is: A. Headers.
Headers are bricks that are laid perpendicular to the face of the wall. They are used to support the weight of the wall above and to provide stability. Headers are typically laid every fourth course of bricks, but the spacing may vary depending on the thickness of the wall and the type of brick being used.
Stretchers are bricks that are laid parallel to the face of the wall. They are used to form the main structure of the wall. Stretchers are typically laid every other course of bricks, but the spacing may vary depending on the thickness of the wall and the type of brick being used.
Brick bats are small pieces of brick that are used to fill in the spaces between the headers and stretchers. They are not structural bricks and are not essential for the stability of the wall.
Queen closers are bricks that are cut in half lengthwise. They are used to fill in the spaces at the ends of walls. Queen closers are not structural bricks and are not essential for the stability of the wall.
In conclusion, headers are the best type of brick to use for hearting of thicker walls. They are strong and provide stability to the wall.