Question

If the ratio of the arc length to r is 1, then the measure of is 1 radian.

Answer 1

Well the radian is the measure of the radius
this line measure is then ligned up to the circumference
mearuse of 1 raidan is always equal to the measure of the radius therfor the true statements are

ratio of arc legnth to r is always equal to 1

I'm not sure what 'if the measure of is'

but I think the answer is
if the measure of is 1 radis, than the arc legnth is r since r reaprensents radius

so first and third choice are correct