Questions on Auto collimator

Q1-Auto collimator is used to check
(a) Roughness 
(b) Flatness
(c) Angle
(d) Automobile balance
.
Q2-An autocollimator is used to
(a) measure small angular displacements on flat surface
(b) compare known and unknown dimensions
(c) measure the flatness error
(d) measure roundness error between centers