Which of the following statements represents a correctly structured transaction?

a$.)$

BEGIN;

COMMIT;

insert into album $($album$\_$id$,$ title, artist$\_$id$)$ values $(400,$ 'New Album', $5)$;

insert into playlist $($playlist$\_$id$,$ name$)$ values $(40,$ 'Top $40\text{'}),(41,$ 'Top $40\text{'}),(42,$ 'Top $40\text{'})$;

insert into album $($artist$\_$id$,$ title, album$\_$id$)$ values $(1,\text{'}$My Album', $348)$;

COMMIT;

b$.)$

BEGIN;

insert into album $($album$\_$id$,$ title, artist$\_$id$)$ values $(400,$ 'New Album', $5)$;

insert into playlist $($playlist$\_$id$,$ name$)$ values $(40,$ 'Top $40\text{'}),(41,$ 'Top $40\text{'}),(42,$ 'Top $40\text{'})$;

insert into album $($artist$\_$id$,$ title, album$\_$id$)$ values $(1,\text{'}$My Album', $348)$;

COMMIT;

c$.)$

BEGIN

insert into album $($album$\_$id$,$ title, artist$\_$id$)$ values $(400,$ 'New Album', $5)$

insert into playlist $($playlist$\_$id$,$ name$)$ values $(40,$ 'Top $40\text{'}),(41,$ 'Top $40\text{'}),(42,$ 'Top $40\text{'})$

insert into album $($artist$\_$id$,$ title, album$\_$id$)$ values $(1,\text{'}$My Album', $348)$

COMMIT

d$.)$

BEGIN

insert into album $($album$\_$id$,$ title, artist$\_$id$)$ values $(400,$ 'New Album', $5)$;

insert into playlist $($playlist$\_$id$,$ name$)$ values $(40,$ 'Top $40\text{'}),(41,$ 'Top $40\text{'}),(42,$ 'Top $40\text{'})$;

insert into album $($artist$\_$id$,$ title, album$\_$id$)$ values $(1,\text{'}$My Album', $348)$;

COMMIT;