A string can a set of characters represented by a row vector of characters. If s$1=$'John Carter', s$2=$'a manager', write a command to use $s1$ and $s2$ to concatenate to a new string $s=$ 'John Carter is a manager'.

$s=s1,\text{'}$is$\text{'},$ s$2$

$\text{'}$s$1\text{'},\text{'}$is$\text{'},\text{'}$s$2\text{'}]$

$,$ is$,s2$

is $\text{'},$ s$2]$