Please solve this query experts.

 

Dear Student,
Answer to your question is given below:
Given, $y = -x + 3$
Comparing it with the general equation of straight line,
$y = mx + c$
where m is the slope of the line.
we get, m = -1
Now we know that,
$$\begin{gathered} m=\tan \theta \\ \Rightarrow \theta ={\tan }^{-1}(-1) \\ \Rightarrow \theta ={135}^o \end{gathered}$$
Hence option(2) is the correct choice.
Regards,