To pick the “novel” antidepressant, rank the candidates by era and mechanism.
$\text{Vilazodone} \Rightarrow \text{SPARI (2011)}$ - serotonin partial agonist + reuptake inhibitor; it both blocks the serotonin transporter and partially agonises the $5\text{-}HT_{1A}$ autoreceptor, which is thought to give a faster onset and fewer sexual side effects than classic SSRIs.
$\text{Trazodone} \Rightarrow \text{SARI}$, an older serotonin antagonist/reuptake inhibitor used at low dose mainly as a hypnotic.
$\text{Imipramine, Amitriptyline} \Rightarrow \text{TCAs}$, the oldest generation, acting on serotonin and noradrenaline reuptake with anticholinergic and cardiac liabilities.
Among these, only vilazodone represents a recently developed molecule with a distinctive dual serotonergic mechanism, so it is the answer.
\[\boxed{\text{Novel antidepressant} = \text{Vilazodone}}\]