linear simply means the higest power of any placeholder is 1 and positive
first one, all 1, linear, A
2nd one
that is actually 6y^-1, that is negative exponent so not linear, so B
3rd one: correct, that is just x^1 times 1/2 minus 3 so linear, so A
4th one, x^3, duh, not 1, non-linear, B
5th one, fist degree, linear, A
A
B
A
B
A