Final answer:
Formal assessment for special education within RTI typically occurs after Tier 3 intervention, which is after more intensive, individualized support has been provided and the student still shows a lack of response.
Step-by-step explanation:
In Response to Intervention (RTI), formal assessment for special education identification typically occurs after Tier 3 intervention. This means that before a formal assessment is conducted, the student will have gone through multiple levels of interventions. Tier 1 intervention includes universal screening and group interventions that are implemented with all students. If a student does not respond to Tier 1 supports, they are moved to Tier 2 intervention, which involves more targeted support. Finally, Tier 3 intervention offers more intensive, individualized support and is provided before considering a formal special education assessment. Therefore, option c) 'Occurs after Tier 3 intervention' is the correct completion for the statement.