Let’s break this down.

**1. Current use of hybrids**  
Iberdrola has issued hybrid bonds since 2013 and did so in 2021 or 2022. In the 2022 balance sheet, equity includes €–932 million “Ajustes Por Cambio De Valor” (after OCI movements linked partly to hedging and hybrids). There are also “Instrumentos de capital con características de pasivo financiero” of €576M noncurrent and €87M current — these represent hybrids classified as debt under IFRS, but which receive partial equity credit from rating agencies. The presence of hybrids and history of active use signal that management understands and values this instrument.

**2. Financial profile and leverage**  
- S&P Net Debt / EBITDA (2022): 3.91x  
- S&P FFO / Net Debt (2022): 19.65%  

These metrics are consistent with a solid investment-grade rating (likely ‘BBB+’ to ‘A-’ range). The leverage is somewhat elevated for a utility, but not alarming. Moody’s adjusted leverage trend is “Stable”, indicating no imminent downgrade pressure.

**3. Refinancing and capex needs**  
Iberdrola’s capex is large (€6.3bn purchase of PP&E, growing asset base). The swap curves show materially higher rates in 2022 vs 2020–2021 (5Y from -0.35% avg to +1.73%), raising the relative cost of hybrid vs fixed-rate senior debt. However, the **sub-sen delta for iBoxx EUR Non-Financial IG** averaged 2.295% in 2022, which is the all-in yield for hybrids. The Company’s average cost of debt will have risen, but hybrids may still be only moderately more expensive than senior.

**4. Guidance checklist alignment**  
The description for 7.5% mentions:  
- Moderate refinancing or acquisition needs  
- Rating headroom moderately constrained  
- Hybrid issuance meaningfully improves adjusted leverage metrics  
- Cost of hybrid will slightly increase current cost of debt  

This fits Iberdrola’s profile:  
- Capex is high, but organic; acquisitions are bolt-on, not transformational.  
- Leverage is manageable but could benefit from equity credit.  
- The company already has hybrids and likely operates around 7–10% of adjusted capital in hybrids.  
- Cost of hybrid is higher than in 2020–2021, but still reasonable relative to benefits.

0% is too low given ongoing issuance history and capex. 15% is too high — no downgrade crisis or transformational M&A. 3.75% would be too conservative for a seasoned issuer. 11.25% could be considered if they had an acquisition pipeline, but there’s no evidence of imminent large M&A. 7.5% is the sweet spot.

<answer>7.5%</answer>