Yeah

"Yeah" is a more casual way of saying "yes". 

Say this to agree with something that a person said:

Yeah, no problem.

Yeah, I actually did it myself.

You can also say "yeah" when you're going to disagree but you want to make your disagreement sound a little softer.

Yeah, but then it'll be blocking one of the outlets.

"Yeah" sounds less formal than "yes." 

(something) sounds like (something)

When you want to comment on what a person talked about, you can use the phrase "___ sounds ___":

Your job sounds fun.

That sounds complicated.

When you use this expression, the word that follows "sounds" should be an adjective ("fun", "complicated", "heavy", "expensive", etc.)

If you want to use a noun instead of an adjective, the phrase is "___ sounds like ___":

That sounds like a lot of work.

Your town sounds like the town I grew up in.

Those guys sound like a fun group.

a good option

The word "option" means "choice". You can use it when you're talking about making a decision:

A: Where should we go?

B: I don't know. What are our options?

A: Why did you do that?

B: Because I had no other option!

"Option" is just a tiny bit more formal than "choice". For most situations, you can use either word. But there are some collocations that usually use "option" instead of "choice":

• explore your options
• examine your options
• keep your options open