The cross-sectional area of the conductors or optical fiber tubes (metallic or nonmetallic) permitted in a seal in a Zone 0, Zone 1, or Zone 2 location shall not exceed? of the cross-sectional area of a rigid metal conduit of the same trade size unless it is specifically listed for a higher percentage of fill.
a) 25%
b) 50%
c) 75%
d) 100%