RSS has two official full forms that are both correct: 'Really Simple Syndication' (version 0.91, 0.92, 1.0, 2.0) and 'Rich Site Summary' (version 0.9). Both names have been used at different points in RSS's evolution, and both are considered valid. Therefore, option C ('Both 1 and 2 are true') is the correct answer as it acknowledges both naming conventions.