Figure $4$

Panel $($a$)$ represents an individual firm's cost curves in a perfectly competitive market, and panel $($b$)$ represents the market conditions $($thus$,$ short$-$run and long$-$run responses of the perfectly competitive market.$)$

$($a$)$

$($b$)$

Refer to Figure $4.$ Assume that the market starts in equilibrium at point $A$ in panel $($b$)$ in a perfectly competitive market. Panel $($a$)$ represents cost curves of an individual firm in this competitive market. An increase in demand from Demando t Demand ${?}_1$ will increase the price from P$1$ to P$2,$ causing economic profit for an existing firm in the short run. This will cause new $q,$ of firms and eventually $q,$ the number of firms in the market, shifting supply curve from Supply oto Supply ${?}_1,$ and reach a new long$-$run equilibrium at point $q,($choose one among A$,$ B$,$ C$,$ and D$)$

Provide multiple answers with commas $q,,,$