Q1. What is the passage mainly about?

1. AHow to cook with collagen
2. BWhether eating collagen helps your skin
3. CWhy sleep is important
4. DHow companies make drinks

コラーゲンを食べると肌に良いのかどうかがテーマなので B。

Q2. What does your body do with the collagen you eat?

1. AIt sends it straight to your skin.
2. BIt keeps it in your stomach.
3. CIt breaks it into very small pieces.
4. DIt turns it into sugar.

Your body breaks it into very small pieces before it uses it. とあるので C。

Q3. In this passage, "surer" means ...

1. Amore certain to work
2. Bmore expensive
3. Cmore delicious
4. Dmore difficult

surer は sure（確かな）の比較級で「より確実な」。睡眠と日焼け対策の方が確実だという意味なので A。

Q1. What happens to collagen after we eat it?

1. AIt goes directly to the skin.
2. BIt is broken down into amino acids and short peptides.
3. CIt stays in the stomach.
4. DIt changes into fat.

it is broken down ... into amino acids and short peptides before it is absorbed とあるので B。

Q2. What did the 2005 Japanese study find?

1. ACollagen cannot be absorbed at all.
2. BSkin became younger in one day.
3. CCompanies paid for all the research.
4. DSmall collagen-based peptides appeared in people's blood.

found small collagen-based peptides in people's blood とあるので D。

Q3. What does the last sentence suggest?

1. ACompany funding might affect the results of collagen studies.
2. BCollagen works better without company funding.
3. CAll collagen studies are false.
4. DThe 2023 review was not published.

企業資金のない研究では効果がはっきりしなかったことから、資金提供が結果に影響しているかもしれないと推論できるので A。

Q1. What hypothesis did the 2005 Japanese study raise?

1. ACollagen fragments might signal skin cells to produce collagen.
2. BCollagen goes directly to the skin without being digested.
3. CGelatin is harmful to the blood.
4. DAmino acids cannot be absorbed.

That led to the hypothesis that these fragments might act as signals, telling skin cells to make more collagen とあるので A。

Q2. What did the 2025 analysis find when studies were grouped by funding source?

1. AIndustry-funded studies showed no effect.
2. BAll studies showed a large effect.
3. CThere was no effect among studies without industry funding.
4. DOnly high-quality trials showed an effect.

Among trials without industry funding, and among the high-quality ones, the effect disappeared とあるので C。

Q3. Why does the author mention that changes are measured with instruments?

1. ATo show that the instruments were broken
2. BTo prove that collagen works
3. CTo explain why the studies were funded by companies
4. DTo point out that a statistically significant change may not be visible

a change that counts as statistically significant may not be visible in the mirror とあり、統計的な差と見た目の差は別だと指摘しているので D。