Final answer:
The correct sentence with proper punctuation is: Laura has an Australian cattle dog. I have a miniature Schnauzer.
Step-by-step explanation:
The correct sentence with proper punctuation is: Laura has an Australian cattle dog. I have a miniature Schnauzer. Punctuation is essential in writing as it helps to convey meaning and clarify the intended message. In this case, using a period after the first sentence and capitalizing the 'I' in the second sentence indicates two separate thoughts or statements.
Learn more about Punctuation in English sentences