title: Use case diagrams use of <<extend>>
body: <p>in my system "compare modifications" and "save image" are optional activities. but they are presented to the user. user may or may not use them. is this the correct form showing the scenario in use case diagram? Imstill new to UML , if I'mnot wrong i think extend keyword can be used to show optional activities.   </p>
  
  <p><img src="https://i.stack.imgur.com/b8Tsr.jpg" alt="enter image description here"></p>