what is the time complexity of the following code

for $($int i $=$ n; i $>0$; i$--)$

for $($int j $=0$; j $<$ i; j$++)$

count $+=1$;

Select one:

a$.$ O $($n$)$

b$.$ O $($n$^2)$

c$.$ O $($n log $($n$))$