The researchers devised a second procedure to measure static friction. They removed the string from a block, placed the block at rest on a board, and raised one end of the board until the block began to slide. To determine the static friction force on the block when sliding began, which of the following measurements did they make?A) Time it took for the block to slide down the boardB) Distance the block slid down the board before coming to rest C) Mass of the board D) Angle of the board with respect to the horizontal