A platitude is a statement that is simply accepted as true without being questioned or analyzed. It is often used to express a truism or an obvious fact. For example, "The sun rises in the east and sets in the west" is a platitude.

The most appropriate word to substitute for "statement that is obviously true" is:

Option 2: platitude

1. Fatal: This word means something that causes death or is capable of causing death. It has no relevance to a statement that is obviously true.

2. Platitude: A platitude is a statement or remark that is overused and lacks originality, often because it is so obviously true that it has become cliché. In the context of the original statement, "statement that is obviously true," a platitude perfectly fits because it describes a statement that is widely accepted and lacks depth or novelty.

3. Conventicle: A conventicle refers to a small, secret, or unauthorized religious meeting or gathering. It has no connection to the concept of a statement that is obviously true.

4. Privilege: Privilege refers to a special advantage, right, or benefit granted to a particular group or individual. It does not convey the idea of a statement being obviously true.