Weaken the hypothesis

Some reading questions describe a situation and a hypothesis, then ask which finding, if true, would most weaken it.
To weaken means to make the explanation less believable — the opposite of strengthening it.
You are looking for evidence that pushes against the claim.

The key move is to ask what the hypothesis predicts, then find the choice showing the opposite happens.
If the hypothesis says a mural shows communal life, a choice describing solitary activity works against it.
If the hypothesis says exercise improves the brain, a choice showing no improvement works against it.

It helps to sort the choices into three groups.
A choice that weakens the hypothesis contradicts its prediction.
A choice that strengthens it agrees with the prediction.
A neutral choice is true but irrelevant.
Only the weakening choice can be the answer.

Here is the format.
Passage: "A cafe owner notices the shop is busier on days she bakes fresh bread, and hypothesizes that the smell draws people inside."
Question: which finding, if true, would most weaken her hypothesis?
Choice (A): "On fresh-bread days she also happens to run a large discount on coffee."
Choice (B): "Customers say they cannot smell the bread from outside the shop."
Choice (B) weakens the hypothesis, because if no one can smell the bread outside, the smell cannot be what pulls people in.
Choice (A) offers a different possible cause but does not by itself disprove the smell idea.

Archaeologists uncover ancient murals covered in scenes of people gathered together, and they hypothesize that the murals were made to celebrate the community's shared, communal life.
Which finding, if true, would most weaken this hypothesis?
(A) A later mural at the same site is shown to depict a single person hunting entirely alone.
(B) The bright pigments used in the murals were made from local minerals.
Choice (A) weakens the hypothesis, because a scene of solitary activity works against the idea that the murals celebrate communal life.
Choice (B) is neutral: where the paint came from says nothing about the murals' purpose.

A health researcher reviews several studies and hypothesizes that regular exercise improves memory and thinking in older adults.
Which finding, if true, would most weaken this hypothesis?
(A) A large new study finds no difference in memory scores between older adults who exercised regularly and those who did not.
(B) The older adults in one study also enjoyed exercising outdoors.
Choice (A) weakens the hypothesis, because finding no difference directly contradicts the claim that exercise improves thinking.
Choice (B) is neutral: enjoying the outdoors does not bear on whether exercise helps memory.

A climate scientist hypothesizes that El Niño years bring heavy rainfall and flooding to the coast of South America.
Which finding, if true, would most weaken this hypothesis?
(A) During several recent El Niño years, that coast instead suffered prolonged droughts.
(B) El Niño is known to affect weather patterns in many parts of the world.
Choice (A) weakens the hypothesis, because droughts are the opposite of the flooding the hypothesis predicts.
Choice (B) is neutral: that El Niño is widespread says nothing about rainfall on this particular coast.