HELP PLZZZZZZZZZZZZ To convert from spray irrigation to drip irrigation, you must remove spray nozzles from risers and replace with?

a
With an adaptor drip head which has 1/4" ports for 1/4" drip tubing?
b
Just cap off all risers sticking out of the ground?
c
Add 1/2" tubing to the riser?
d
Rebuild the irrigation system from the beginning ?