Pretty much understand everything except one thing, please help me 7Sage wizards

Most opera singers who add demanding roles to their repertoires at a young age lose their voices early. It has been said that this is because their voices have not yet matured and hence lack the power for such roles. But young singers with great vocal power are the most likely to ruin their voices. The real problem is that most young singers lack the technical training necessary to avoid straining their vocal cords—especially when using their full vocal strength. Such misuse of the cords inevitably leads to a truncated singing career.

E)Most young opera singers who sing demanding roles strain their vocal cords

Young Opera singers -most> loose voice

Young Opera singers -most> lack tech training to avoid loosing voice

Isn’t the valid inference

A most B

A most C

___

A some C ???

I thought A most C was invalid…..