ith your cards again in the same position as Figure $8$A$-2$C$,$ place the pencil point at the X and slowly pull the lower left tab of Card $2$ toward you while moving your pencil away from you, drawing a line along the slit of Card $2.$ Card $2$ is rotating counterclockwise. The line you drew is $\_\_\_\_\_\_.$

a$.$straight

b$.$curved