Analyze the following statements in the context of an abstract method in C# and select the appropriate choice.
S1: An abstract method can never be instantiated.
S2: Abstract methods should always have a sealed modifier.
S3: Abstract methods are always implicitly virtual
- Only S1 and S2 are true
- Only S2 and S3 are true
- Only S1 and S3 are true
- All S1, S2 and S3 are true