If the ratio of the arc length to r is 1, then the measure of is 1 radian.
the ratio of arc length to r is always equal to 1.
if the measure of is 60, then the arc length is r.
if the measure of is 1 radian, then the arc length is r.
which options are true?

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