A plane perpendicular to the polar axis will never form what line on the Earth’s surface? （）

A.great circle
B.loxodromic curve
C.small circle
D.gnomonic curve

A.be green in color
B.have an even number
C.be left to port when entering from seaward
D.be cylindrical in shape

A.fixed red light
B.Morse (A) white light
C.green light
D.flashing red light