查询客户姓名以及所开通的远程登录业务的信息，没有申请远程登录业务的客户也要出现在结果集中，下列sql语句正确的是：( )
select a.id,a.real_name,s.unix_host,s.os_username
from account a cross join service s on a.id = s.account_id;
select a.id,a.real_name,s.unix_host,s.os_username
from account a join service s on a.id = s.account_id;
select a.id,a.real_name,s.unix_host,s.os_username
from account a right join service s on a.id = s.account_id;
select a.id,a.real_name,s.unix_host,s.os_username
from account a left join service s on a.id = s.account_id;
