&lt;?php # echo &quot;Hello world&quot;; echo &quot;# Hello world&quot;; ?&gt;
A. # Hello world
B. Hello world# Hello world
C. Hello world
D. Error
Answer:A
&lt;?php # echo &quot;Hello world&quot;; echo &quot;# Hello world&quot;; ?&gt;
A. # Hello world B. Hello world# Hello world C. Hello world D. Error
Explanation: # is a single line comment.