Consider the following Python script. Which line of code will cause an error?

$1$ a $=$ "Hello"

$b=$ 'friend'

$c=,$ how are you today?"

$d=23$

print $(a+b+c)$

$pr{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(b+c+d)$

print$($d$)$

$2$

$6$

$7$

$4$