The underlined phrase "suffer from" most probably means （）

A．have a curable disease in their eyes
B．have eyes that are not exactly the right shape
C．have a difficulty that can be corrected by an operation
D．have an eye difficulty that cannot be corrected by glasses

A．only when we cannot see perfectly
B．only when we can see well
C．even if we can see well
D．only when we realize how important our eyes are