Commas with conjunctions

I play tennis.

I swim.

Which coordinating conjunction is best?

• and

• but

• or

On Saturday we go to the park.

On Sunday we go to church.

• and

• but

• or

I want to go shopping.

I don't have money.

• and

• but

• or

We can go to the park.

We can go to a movie.

• and

• but

• or

Which sentence is correct? comma or no comma?

• You can use the blue pen or the red pen.

• You can use the blue pen, or the red pen.

Which sentence is correct? comma or no comma?

• We can read a book or we can watch TV.

• We can read a book, or we can watch TV.

Which sentence is correct? comma or no comma?

• I eat healthy but I don't exercise.

• I eat healthy, but I don't exercise.