Answer: Use S3 Standard. Use an S3 Lifecycle rule to transition the reports to S3 Glacier Deep Archive after 7 days.

## Explanation **Key Requirements Analysis:** 1. **Frequent access during first week** → Need Standard storage class initially 2. **Stored for several years** → Long-term archival needed 3. **Retrievable within 6 hours** → Glacier retrieval times (3-5 hours for Standard retrieval) meet this requirement 4. **Most cost-effective solution** → Need to minimize storage costs for long-term archival **Option Analysis:** **A. S3 Standard → S3 Glacier after 7 days** - ✅ Standard for first week (frequent access) - ✅ Glacier for long-term storage - ✅ Retrievable within 6 hours (Glacier Standard retrieval: 3-5 hours) - ❌ Not the most cost-effective (Glacier Deep Archive is cheaper) **B. S3 Standard → S3 Standard-IA after 7 days** - ✅ Standard for first week - ❌ Standard-IA is for infrequent access (minimum 30 days storage charge) - ❌ Not suitable for "several years" storage (too expensive for long-term) - ❌ Doesn't meet "most cost-effective" requirement **C. S3 Intelligent-Tiering** - ✅ Automatically moves objects between tiers - ❌ Intelligent-Tiering doesn't transition to Glacier storage classes - ❌ More expensive than direct lifecycle to Glacier Deep Archive - ❌ Not the most cost-effective **D. S3 Standard → S3 Glacier Deep Archive after 7 days** - ✅ Standard for first week (frequent access) - ✅ Glacier Deep Archive for long-term storage (cheapest option) - ✅ Retrievable within 6 hours (Glacier Deep Archive Standard retrieval: 12 hours) - ❌ **WAIT: This doesn't meet the 6-hour retrieval requirement!** **Critical Issue:** The question states "retrievable within 6 hours" but Glacier Deep Archive Standard retrieval takes 12 hours. However, looking at the options: - **Glacier** (Option A): 3-5 hours retrieval - **Glacier Deep Archive** (Option D): 12 hours retrieval (doesn't meet 6-hour requirement) **Correction:** Based on the retrieval requirement of "within 6 hours", Option A is actually correct because: 1. Glacier retrieval times: Standard retrieval = 3-5 hours (meets 6-hour requirement) 2. Glacier Deep Archive retrieval times: Standard retrieval = 12 hours (does NOT meet 6-hour requirement) **Therefore, the correct answer should be A.** **Why A is the most cost-effective while meeting all requirements:** 1. **First week:** S3 Standard for frequent access 2. **After 7 days:** Transition to S3 Glacier (cheaper than Standard-IA for long-term) 3. **Retrieval:** Glacier Standard retrieval = 3-5 hours (meets 6-hour requirement) 4. **Cost:** Glacier is significantly cheaper than Standard-IA for multi-year storage **Note:** The question asks for "MOST cost-effective" solution that meets ALL requirements. While Glacier Deep Archive (Option D) is cheaper, it doesn't meet the 6-hour retrieval requirement. Therefore, Option A is the correct choice.