Hello!
I don't think it would be a bad idea at all to focus on the energy sector, especially if you feel you can give a stronger and more original answer there.
Bird & Bird has a really strong reputation across multiple sectors, not just tech / media, and they'll be looking to see that you've done your research into their wider expertise.
I'd say the most important thing is to give a strong, well-reasoned answer. If you've got a clear idea for the energy sector, it's much better to go with that than force something for tech / media that you're not confident in. Even if you have spoken about IP and tech in your 'Why
Bird & Bird' answer, they will expect you to have interests in other areas as well, and it might even be advantageous to discuss another sector in your answer.