What's the name of the waterfall? -i . a)don't know b)didn't know c)haven't known

А) don't know

This school year we have visited many interesting places. - верно.
We have gone to the Excursion of the museum this month. - после глагола go только to 
It was interesting because there were a lot of beautiful pictures in the museum which we liked very much. - здесь не скажешь в Present Prefect
Also the museum guide has told us very interesting history about these famous pictures. - так тоже не говорят, но с точки зрения грамматики предложение построено верно.
We were happy because we have already gone to this excursion and have learnt a lot. - то же как и в предыдущем предложении, лучше было бы просто в Past, но раз задание только в Present Perfect, пусть будет так.
Best of all I liked waching the pictures which I have never seen before. - Больше всего мне понравилось рассматривать картины, которые я никогда не видела раньше.

- You had it, Ana! Did you remembered how I gave it to you so you could read it?- Jack sat down still having his eyes on Ana who was trying to find a paper that Jack gave to her last monday.
- I knew that I'm going to lose your paper, Jack... - she was saying while she was looking at her table - Oh, I found it !
- Ana, put it on your table. I just want to make sure that everything is okay to my papers - politely asked Jack.
- It was a terrible idea - said Ana, she got that paper and gave it back to Jack...
- You wrote pizza delivery phone number on it!? I told you that I'll sent to office in Mexico!? Pack your things, Ana! - said Jack, then he came closer and said softly:
-You have only 10 seconds to run away. GO!
Ana started running. She didn't want to go to Mexico.