Given the following code, what is the final value of cList$[6]?$

clist $=\left[\begin{array}{cccccc}4& 7& 10& 20& 77& 38\end{array}\right]$

dList $=[21,63]$

clist.extend$(dList)$

a$)38$

b$)77$

c$)21$

d$)$ The extend operation causes an error