Final answer:
Silicon-28 is inferred to be the most abundant silicon isotope because the atomic mass of silicon (28.086 amu) is closest to the mass number of Silicon-28.
Step-by-step explanation:
The question asks which isotope of silicon is the most abundant based on the atomic mass of silicon, which is 28.086 amu. The atomic mass of an element is the weighted average of all its isotopes present in nature. Since the atomic mass of silicon is very close to the mass number of the Silicon-28 isotope and considering that the atomic mass typically leans towards the most abundant isotope, we can infer that Silicon-28 is the most abundant isotope (Option A). To confirm this, we would need the actual abundance percentages of each isotope, but generally, the mass number closest to the atomic mass represents the most abundant isotope.
Given that the atomic mass of Silicon-28 would be close to its mass number of 28, and since atomic masses of isotopes are close to but not the same as their mass numbers, as observed with chlorine and boron isotopes in various examples, we can deduce that Silicon-28 is the most abundant of the three silicon isotopes listed.