[B]

1. Betty Botter had some butter,
"But," she said, "this butter's bitter.
If I bake this bitter butter,
it would make my batter bitter.
But a bit of better butter
that would make my batter better."

2. A big black bug bit a big black bear,
made the big black bear bleed blood.

3. Betty better butter Brad's bread.

4. A bloke's back bike brake block broke.