Thomas is most likely using Follow TCP Stream. This Wireshark feature reconstructs the bidirectional application data carried over a TCP connection by reassembling packets in sequence into a readable conversation view. When traffic is unencrypted HTTP, the reassembled stream can reveal full request/response content, including URLs, headers, form parameters, and—critically in this scenario—usernames and passwords transmitted in clear text (for example, within POST body parameters).

The scenario’s language is a direct match: “reconstruct entire conversations between browsers and the server” and “reassembles packet data into a readable stream.” That is exactly what Follow TCP Stream does: it groups packets that belong to the same TCP session and displays the payload as contiguous data, making it far easier than manually inspecting individual packets. This is commonly used during assessments and investigations to understand what data was exchanged, validate whether sensitive data is exposed, and confirm whether protections like TLS are properly applied.

Why the other options are not correct:

Filtering by IP Address (A) helps narrow the packet list to specific hosts but does not reconstruct conversations.

Display Filtering by Protocol (B) can isolate HTTP packets but still leaves the analyst to interpret individual packets without full reassembly.

Monitoring the Specific Ports (C) similarly narrows traffic (e.g., TCP/80 for HTTP) but does not present a reassembled readable session.

Because the goal is quick, readable reconstruction of HTTP login sessions over TCP, the correct answer is D. Follow TCP Stream.