Help with 1 and 2 (earth and science)

The Earth is 4.6 Billion years old.

QUESTION 2:

Option A is the correct answer.

Hope it helps:)

answer; a male inherits only one allele of the x-linked gene controlling hair color;

you didn't give any options but heres what i can tell you: an inference is likely to change based on additional observations. the latter is something that you have seen or sensed using your sensory organs while the former is like a conclusion out from what you have observed.