Which of the following is a candidate key of PORT?

$\{$Port Name, Country$\}($a candidate key with $2$ attributes together$)$

$\{$Port Name, Country, Port Manger$\}($a candidate key with $3$ attributes together$).$

Country

$\{$Port Name, Port Manger$\}($a candidate key with $2$ attributes together$)$

Port Name

Port Manager