Which of the folling statement below is correct ?

Diagonal tension is caused by the combined action of longitudinal tension and the transverse shearing stresses

Shear reinforcement in the form of vertical bars is known as stirrups

According to IS : 456 - 1978, if the shear stress is less than one -tenth of compressive stress $\left({\sigma }_{cb}\right)$ in concrete at extreme fibe, no shear reinforcement is necessary

all of the above