Is these correct:

Question

Simple-Dolphins are very intelligent, social creatures.

Compound- Dolphins are very intelligent and social creatures.

Help on these on:

Simple- Katy is thinking she might like to become a marine biologist one day.

Answer 1

That is not a compound sentence.

The last one is not a simple sentence.

Study this site.

http://www.eslbee.com/sentences.htm

Answer 2

Then how do i turn the 1 one into it

Answer 3

Study the site I posted. It explains a compound sentence.