Wordpress - Query Custom Post by Taxonomy Category

There are 3 ways of doing that:

a)

...
'category_name' => 'category-1'
...

b)

...

'taxonomy' => 'category',
'term' => 'category-1',

...

c)

...
'tax_query' => array(
  array( 'taxonomy' => 'category', 'field' => 'slug', 'terms' => array( 'category-1' ) )
)
...

More info: http://codex.wordpress.org/Function_Reference/WP_Query