Consider an entity set Spaceship, with attributes name, sequence number (seq_num), country, flight date, and captain. Assume that the following conditions hold: (1) No two space ships have the same name and sequence number (seq_num), (2) no two space ships have the same combination of captain and flight date, (3) each space ship has a name, a seq_num, and a country, and (4) not all space ships have been flown or have a captain.

(a) List all candidate keys and all superkeys for this entity set.

(b) Write a create table statement that defines a relation appropriate for this entity set.