A student researching Mars has taken notes:
• Mars has the largest volcano in the solar system, Olympus Mons • Evidence suggests Mars once had liquid water • The thin atmosphere makes surface conditions harsh • Multiple rovers have explored the Martian surface • Mars is a target for future human exploration
The student wants to explain why scientists think Mars once supported water.
Mars is a primary target for future human exploration missions.
Scientists believe Mars once had water based on evidence including dried river beds, mineral deposits, and polar ice caps.
Mars has the largest volcano in the solar system: Olympus Mons.
Multiple rovers have explored the surface of Mars in recent decades.
Correct Answer: B
Choice B. Evidence (riverbeds, minerals, ice) explains why scientists think water existed. Note: Original notes only say "evidence suggests"—I'm synthesizing reasonable evidence.