$($BGP$)$ Consider the network shown below. Assume all links have same cost, $1.$ Suppose AS$3$ and AS$2$ are running ISIS, while AS$1$ and AS$4$ are running OSPF for their intra$-$AS routing protocol, respectively. eBGP and iBGP are used for the inter$-$AS routing protocol. Initially, suppose there is no physical link between AS$2$ and AS$4.$ Once router $1d$ learns about $x,$ it will put an entry $($destination$,$ interface$)$ in its forwarding table.

a$)$ What will be the entry added by $1d.$ Explain in one sentence.

b$)$ Now suppose that there is a physical link between AS$2$ and AS$4,$ shown by the dotted line. Suppose router $1d$ learns that $x$ is accessible via AS$2$ as well as via AS$3.$ What entry will be added to $1d\text{'}$s forwarding table? Explain in one sentence.

c$)$ Now suppose there is another AS$,$ called AS$5,$ which lies on the path between AS$3$ and AS$4($not shown in diagram$).$ Suppose router $1$d learns that $x$ is accessible via AS$3$ AS$5$ AS$4$ as well as via AS$2$ AS$4.$ What will be the entry added by $1d.$ Explain in one sentence.