Final answer:
Rock samples showing that only one-sixteenth of a radioactive element remains after a half-life of 100 million years indicate the rocks are 400 million years old. Without further details, it's challenging to identify the exact celestial body, but lunar samples have diverse ages, some dating around this time.
Step-by-step explanation:
When analyzing rock samples from another object in our solar system using radiometric dating, the finding that only one-sixteenth (1/16) of the original radioactive element remains indicates that the rocks went through four half-lives, as 1/24 equals 1/16. Given a half-life of 100 million years, the calculation would be 4 half-lives times 100 million years per half-life, resulting in an age of 400 million years for the rock. As these surfaces are covered in similar-aged rocks, it's possible that they are from an object with a global resurfacing event around that time. Considering that Mars, Venus, Mercury, the Moon, and the asteroid Eros are the options given, without more specifics on the surface characteristics or cratering, it's difficult to decisively pick one. However, out of these options, the Moon has a well-studied geological history, and rocks brought back from the Moon have been dated to various ages, including those around 400 million years.