multiple choice question

by ameer
(hyderabad)

which is not an advantage of helium/argon/carbon dioxide mixtures for welding stainless steel?
a.short circuiting transfer can be used for joining thin materials and welding out of position
b.the high heat input of helium produces deep penetration
c.wetting and bead appearance are good
d.they can be used on austenitic stainless steel without fear of hydrogen embitterment

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the answer is b

am I helping with some test here? or are you testing me?