If you're dealing with a custom SObject, then that relationship is going to be a custom field.
Therefore, it'll be
Account__c, and you'll need to use
Account__r.Name1 in your query. That'll be true for both lookup relationships and master-detail relationships.
The only time you can avoid using
__r is when you're dealing with a standard relationship (e.g.
1: If you're just looking for the Id, there's no reason to query up the relationship hierarchy. Just query for the relationship field on your custom object (i.e.
Account__c). If you do need some other piece of data on the related object, then you'll need to use
__r to access it in the query