The last sentence is correct, because the other ones either had periods in the middle or too many commas in them.
Although he is not popular, his reputation is great.
I love to go shopping however I’m on a budget.
Answer:
The shortage of money...
Or maybe they have been failing for a long time
Answer: A good topic would be using science to figure it out.
Explanation: Like cause get some chemicals and mix them then look atte cause.
