A game board consists of 64 squares that alternate in color between black and white

A game board consists of 64 squares that alternate in color between black and white

A game board consists of 64 squares that alternate in color between black and white. The figure below shows square P in the bottom row and square Q in the top row. A marker is placed at P. A step consists of moving the marker onto one of the adjoining white squares in the row above. How many 7-step paths are there from P to Q? (The figure shows a sample path.)

(A) 28 (B) 30 (C) 32 (D) 33 (E) 35

answer： A