Which of the following statement $)$ is $($are$)$ correct?

Border Gateway Security is being improved as the Internet is becoming more centralised.

The domain name system $($DNS$)$ has a hierarchical structure.

Some ISPs conduct DNS hijacking to redirect DNS queries.

DNSSEC uses encryption to protect DNS name records.

IoT devices can be used to launch DDoS attacks.

a$.2,3$ and $5$

b$.3$ and $4$

c$.1$ and $3$

d$.4$ and $5$

e$.1$ and $2$