Relationship between level of significance and hypothesis testing?

A physician wishes to study the relationship between hypertension and smoking habits. From a random sample of 180 individuals, the following results were obtained

At the 5% level of significance, test whether the absence of hypertension is independent of smoking habits.

Hypertension

Smoking habit

Non-smokers

Moderate smokers

Heavy smokers

Yes

21

36

30

No

48

26

19