【名词&注释】
维生素A(vitamin a)、被保险人(the insured)、营业额减少(turnover decrease)、釉质发育不全(enamel hypoplasia)、质发育不良
[单选题]Compared to internal structural plating,the exterior hull plating on a vessel is usually().
A. stronger
B. thinner
C. more corrosion resistant
D. a lower grade steel