When the time period of a sound wave is 0.08s , then what is its frequency?

In this question time period is given then we know that the relationship between time period and frequency formula we put given value in this relation then calculate final answer.

We know that, the relationship between time period and frequency is given as:

Time period $\left(T\right)=1/\nu$
According to question given that,
Time period $\left(T\right)=0.08 \mathrm{s}$
Frequency $\left(f\right)=1 / T$(time period)
$f=1 / 0.08=100 / 8$

$f=12.5 \mathrm{Hz}$

Hence, option 1 is correct.