Objective means that they are "facts", and do not include personal thoughts and beliefs (which is subjective).
In this case, your answers are:
1) Fact:
Facts are made based on data and analysis, and are supported by details and other known "facts" or <em>truths</em>. This means that they are right in any circumstances in most cases, or at least in the given circumstance that is provided.
2) Data:
Data is used to support the fact, which is objective. Without data, the claim would be seen as a opinion, or subjective, in meaning, a "I feel that it is this way". Without data, you will not have facts.
It is not:
3) Opinion:
Opinion is the antonym of Fact, and so if Fact is a answer choice, then Opinion is not. Opinion is based off of feelings, personal knowledge, and personal preferences. While useful in some cases, it is not objective.
4) Theory:
A theory is not objective, because it is a opinion that is provable (but is yet to be proven). This makes it subjective, until proven right.
~
