In Friedel Craft Alkylation of aromatic compounds using $\ce{BF3}$ :
$\ce{BF3}$ acts as a lewis acid
It is used as a catalyst
Amount of $\ce{BF3}$ used in the reaction is almost equal to that of amount of benzene used.
$\ce{BF3}$ acts as a nucleophile.
I am sure about options $1$ and $3$ being correct and $4$ th being incorrect but I am hesitant about option $2$.
Catalyst is a substance that lowers the activation energy and enhances the rate of the reaction, in the end remaining unconsumed.
Now, what Lewis Acids do is that they make halogens stronger electrophiles by forming complexes with them. Taking this further we can say that yes they serve as "catalysts" in the reaction because otherwise the reaction would have been lot slower.
However, the given answer is $1,3$. Is my reasoning correct and the answer wrong? Is it functioning as a catalyst in the reaction?