For each variable, determine whether it is best thought of as discrete or continuous.

$\backslash$table$[[$Variable$,$Discrete,Continuous$],[($a$)$ The number of damaged chromosomes on a petri dish following irradiation,$0,],[\backslash$table$[[($b$)$ The score $($either $0,1,2,$ or $3$ with $0$ being the worst and $3$ being the best$)$ given by a$],[$quality$-$control manager after an equipment inspection$]],0,0],[($c$)$ The body weight of a preschool child,$0,0],[\backslash$table$[[($d$)$ The total amount of time that customers spend this week listening to telephone "hold" music$],[$while calling $1-800-$PARCELS$]],0,0]]$