Question

the early surveys of the mariner program offered the first close - range images of mars, revealing cratered plains, sweeping canyons, and unexpectedly thin atmospheric conditions. ____ these findings overturned long - held assumptions that the planet might host earth - like environments, prompting researchers to rethink the direction of future exploration missions.
22 mark for review
which choice completes the text with the most logical transition?
a collectively,
b of course,
c likewise,
d however,

Explanation:

To determine the correct transition, we analyze the relationship between the two sentences. The first sentence describes what the Mariner program revealed about Mars. The second sentence states that these findings overturned long - held assumptions. We need a transition that shows how the findings (from the first part) led to the result in the second part.

• Option A: "Collectively" means when taken together as a whole. The findings, when considered together, overturned the assumptions. This makes sense because the various revelations (cratered plains, canyons, thin atmosphere) together had the effect of overturning the old assumptions.
• Option B: "Of course" is used to indicate something that is obvious or expected. But the overturning of assumptions was not an obvious or expected outcome from the initial descriptions of Mars' features, so this is not appropriate.
• Option C: "Likewise" is used to show a similarity or parallel situation. There is no parallel situation being described here; one part is about the discoveries and the other about the effect of those discoveries, so this does not fit.
• Option D: "However" is used to show a contrast. But there is no contrast between the discoveries and the fact that they overturned assumptions. The discoveries led to the overturning, not contrasted with it.

So, "Collectively" is the most logical transition as it shows that the combined findings had the effect of overturning the assumptions.

Answer:

A. Collectively