Final answer:
Option (a), The Austin Powers catchphrase comprised of two 4-letter words and an English accent is 'Yeah, baby!'.
Step-by-step explanation:
The Austin Powers catchphrase that includes two 4-letter words and reflects the English accent is "Yeah, baby!". This iconic line captures the playful and cheeky tone of the character, a British spy from the swinging '60s, brought to the 20th century. The catchphrase has become synonymous with Austin Powers and is often used to evoke the exuberant and freewheeling spirit of the era.