What is the correct syntax in MySQL to declare a variable abc of certain datatype and initiate it with val value?

Select one:

O a$.$ DECLARE DATATYPE$($size$)$abs DEFAULT val;

O b$.$ DECLARE abs DATATYPE$($size$)$ SET DEFAULT val;

O c$.$ DECLARE abc DATATYPE$($size$)$ DEFAULT val;

$$ d$.$ DECLARE DATATYPE$($size$)$abs SET DEFAULT val;