For
helical gears, the helix angle generally ranges from
30 to 45 degrees
45 to 60 degrees
30 to 75 degrees
0 to 30 degrees
0 to 30 degrees
●Helix
angle 
: It is the angle at which the teeth are inclined to the axis
of a gear. It is also known as spiral angle.
●
The helix angle varies from 150 to 250
●
Two mating gear have some helix angle but have teeth of opposite hands.
Hence, the correct option is (D).
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