The data shows Hera S.p.a. (Gruppo Hera) in 2022 delivered strong revenue growth (revenue roughly 20.08b vs 10.56b prior year) and improving equity base and cash flows, but with a sizable increase in noncurrent financial liabilities and overall leverage growth. Key points:
- Equity Attributable To Owners Of Parent: 3,398.4m in 2023 vs 3,200.2m in 2022.
- Liabilities total: 13.4738b (2023) vs 10.6147b (2022).
- Noncurrent Financial Liabilities: 5.6899b (2023) vs 3.716b (2022) — a meaningful rise, signaling higher debt burden.
- Current Liabilities also rose; cash flow from operations in 2022 was modest (CF from operations before WC changes 1.202b in 2022) but cash flow from operating activities only 35.7m in 2022 after outflows—indicating working capital movements and cash generation pressures.
- The company has substantial capex and investing outflows in 2022-2023 (e.g., purchases of PPE and intangibles), implying ongoing capex needs.

Credit assessment guidance: For utilities with high capex intensity and leverage pressure, hybrids can help improve adjusted leverage and equity credit, with hybrid cost manageable if it aligns with current debt cost. Starting position of outstanding hybrids is not provided, but policy cap from S&P is 15% of total adjusted capital. The user’s task is to select a percentage of total adjusted capital to issue hybrids in the next 18 months, given a cap of 15%.

Considering Hera's high capex, rising leverage, and need to preserve investment-grade rating, hybrid issuance can meaningfully improve adjusted leverage with limited cost of debt impact if the hybrids are properly structured. The guidelines indicate:
- If high capex intensity and leverage pressure with need to stabilize trajectory, 11.25% or 15% could be appropriate, with 15% reserved for transformational capex or rating risk.
- Given the current signs (substantial increase in long-term debt and capex), but not necessarily transformational, a moderate to strong step is warranted rather than zero.

Recommended range: 7.5% to 11.25% appears appropriate. It would provide a meaningful cushion to improve adjusted leverage and maintain investment-grade metrics while not overly burdening with hybrid cost. Since the instruction asks to choose exactly one of the provided options, and considering stabilizing leverage needs and rating headroom, 11.25% is a prudent choice, providing substantial leverage optimization without implying a full 15% tilt.

Final answer: <answer>11.25%</answer>