Masculine. The ending ER in french is usually associated with masculinity.
<span>Claire est la fille la plus intelligente de la classe.
Claire is a female, so you add 'la' and a 'e' at the end of intelligent to show its a female.
Claire chante la plus bonne du groupe.
</span>Claire is a female, so you add 'la' and the female version of bon, which is bonne.
<span>
Henri et Paul son les moins patients de tous.
Henri and Paul are male names. Since there is more than one, it is 'les' and add 's' to patients to </span>show its plural.
