Question 12
What does it mean to say the relative atomic mass of oxygen is 16?
The right answer is the one marked above.
That an oxygen atom is 16 times heavier than 1/12 of a carbon-12 atom. It is a comparison, not a number of grams.
"16 times a carbon atom" is wrong — carbon itself has a relative atomic mass of 12, so oxygen is only 16 ÷ 12 times as heavy. An oxygen atom has eight protons.