Let's do it in a general way)
QS: ASSUMPTION in Prof. Z.'s hypothesis
Argument:
In the late nineteenth century, the archaeologist Charles Warren discovered a new way to explore otherwise inaccessible areas, using vertical shafts leading to horizontal tunnels deep beneath the surface. -->C discovered X leading to Y.
These tunnels led directly to those areas. --> Y solves a problem (explore inaccessible areas).
Based on Warren's discovery, Zachi Zweig, a rising star in the archaeological scene, has concluded that similar shafts may be dug on shores in proximity to sunken archeological artifacts, leading to tunnels beneath the sea floor allowing easy access to those artifacts.---> ZZ has concluded that getting Z (similar shafts) leading to Y solving a problem (easy access to artifacts in water)
In general, a similar method is taken to solve different problems. If one establishes the problems are also similar in relevant aspects, it is the assumption)))
A) The specific weight of water and earth are similar, thus creating the same pressure on the tunnel's ceiling. ---->This is about the similarity of one aspect of the tunnels which is a tool to solve a problem. If the tunnel's ceiling is different, then applying similar shafts create a hardship to get the artifacts. So it directly destroy the "easy access" in the conclusion. But keep it now to check other choices.
B) Otherwise inaccessible sunken archeological artifacts can be reached using new technological advancements in the world of marine robotics.-----> This introduces new entity (new tech, advancements) to solve a problem, so a weakener. OUT
C) Tunnels beneath the seafloor and tunnels beneath dry land share the same vertical distance from the surface. ---> This is off for it emphasis the similarity of the application by showing no difference in distance. When this is negated, it shows we can't dug similar shafts. But the argument already established "may be dug" a possibility to solve the problem. So when negated this choice negates the truth of the scope of conclusion. OUT
D) Shafts similar to those dug by the celebrated Warren may be dug on the sea-shore, enabling archaeologists easy access to otherwise inaccessible sunken archeological artifacts.---> Prephase. So this one is just an inference, not assumption. OUT
E) Otherwise inaccessible terrain can be reached below the surface using vertical shafts.----> A strengthener of the premise (First part) OUT.
So it is A