Select all valid applications of bracket notation to access or modify a data structure.

a$.$

my$\_$set $=\{1,2,3,4,5\}$

print$($my$\_$set$[1])$

b$.$

colors $=\{"000000"$: "black", $"$ffffff$"$: "white", $"$dc$143$c$"$:$"$crimson$"\}$

print$($colors$["$dc$143$c$"])$

c$.$

my$\_$string $=$ "zebra"

my$\_$string$[0]="$d$"$

d$.$

my$\_$string $=$ "zebra"

print$($my$\_$string$[0])$