in radiography of a large abdomen which of the following is effective way to minimize the amount of scattered radition reaching the film

in radiography of a large abdomen which of the following is effective way to minimize the amount of scattered radition reaching the film?
1. use of close collimation
2. use of compression devices
3. use of a low-rtio grid
a.1 only
b. 3 only
c.1 and 2 only
d.1,2 and 3