I would say there are two aspects in this question:
Do you have a personal contingency plan? A funder might like to see that you have thought about the possible problems that can arise in your project, including not getting it funded. Showing that you have explored different options shows that you take into account the global context of this project, which is a mindset very useful to be successful in leading a project.
How specific is your proposal to the call? In general, a proposal might not be eligible as is to many funding agencies. For instance, your initial proposal could include only partners from the UK, which makes it ineligible for most EU calls. Answering that you believe the proposed consortium is the best possible one for that particular project, and as such, is not eligible for other agencies, shows that, again, you've thought about the global context of your project.
So the actual answer might depend on your project, whether it is tailored for that specific call or not , whether there are other places it can be eligible or not, whether you would include feedback or not, etc. Answering properly this question demonstrates that you have a vision for your project in a global context, rather than simply answering to the current call.