According to * * * point force balance conditions, there are
Tb=mgtanθ
Tc=mgcosθ
When the ball accelerates, analyze the force on the ball again. As shown in the above figure, gravity and tensile force Tb are synthesized again. According to Newton's second law, there are
TC′-MGC OSθ= ma
TB′= mgtanθ
That is, Tb remains unchanged and Tc increases;
So choose B.