ACEA is a regulated utility with large, stable asset bases and generally predictable operating cash flows, which makes some use of hybrid capital plausible: hybrids can strengthen rating-agency equity credit and support investment needs without immediate common equity dilution.

Key considerations:

- Leverage is already material. At end-2022, financial liabilities were substantial: non-current financial liabilities of about €4.72bn plus current financial liabilities of about €0.62bn, versus equity of about €2.76bn. This points to a debt-heavy capital structure where hybrids could help protect credit metrics.
- Cash generation is solid but not excessive relative to investment needs. Operating cash flow was €727m, while investing cash flow was negative €863m, so free cash flow before financing was negative. This suggests ongoing external financing needs.
- Profitability remained positive but declined: net profit fell from €352m in 2021 to €311m in 2022, and profit attributable to owners declined to €280m. This argues against over-reliance on expensive subordinated instruments.
- Interest-rate and credit-spread conditions worsened significantly in 2022. Swap rates moved sharply upward, and non-financial investment-grade funding spreads also rose. Hybrid bonds, being subordinated and long-dated, would be meaningfully more expensive than senior debt in this environment.
- The company’s regulated utility profile supports moderate hybrid use, but the increased cost of capital and already adequate equity base argue against a high hybrid share.
- A full or majority reliance on hybrids would be inappropriate because hybrids are costly, subordinated, and can create refinancing/coupon-step-up risk. But zero use would miss a useful capital-management tool for a capital-intensive utility.

Overall, ACEA should use hybrid bonds as a meaningful but limited supplement to senior debt and equity, not as a dominant funding source. The best fit among the options is 25%.

<answer>25%</answer>