Question $7$:

Table:

$\backslash$begin$\{$tabular$\}\{|$c$|$c$|$c$|$c$|\}$

$\backslash$hline Quantity & Private Cost & Private Value & Social Value $\backslash \backslash$

$\backslash$hline $1$ & $5$ & $25$ & $35\backslash \backslash$

$\backslash$hline $2$ & $10$ & $20$ & $30\backslash \backslash$

$\backslash$hline $3$ & $15$ & $15$ & $25\backslash \backslash$

$\backslash$hline $4$ & $20$ & $10$ & $20\backslash \backslash$

$\backslash$hline $5$ & $25$ & $5$ & $15\backslash \backslash$

$\backslash$hline $6$ & $30$ & $0$ & $20\backslash \backslash$

$\backslash$hline

$\backslash$end$\{$tabular$\}$

Refer to the table. What is the socially optimal level of output in this market?

X

a$.4$ units

b$.2$ units

c$.3$ units

d$.5$ units