Which liquid is the most viscous? syrup water milk apple juice

Viscosity is the property of a fluid by virtue of which the fluid layers oppose the relative motion between them.It can be considered as the resisting force to the fluid motion.

The force of viscosity between two layers in a fluid is mathematically written as -

Here the negative sign indicates the decrease of velocity with the increase of distance between layers from top to bottom of the liquid and also the opposing nature of force.

F is the viscous force,A is the area of plane lamina

Hence, the substance having greater coefficient viscosity is more viscous than others.

Out of all these options given in the question,the coefficient of viscosity of syrup is more than others.

Hence syrup is more viscous.