Final answer:
In the sentence provided, 'and' is the conjunction that connects 'dog' and 'cat'.
Step-by-step explanation:
The conjunction in the sentence 'The hungry dog and cat were begging for dinner.' is 'and'. This word connects the two nouns 'dog' and 'cat', making them the compound subject of the sentence. Conjunctions are words that join words, phrases, or clauses in a sentence to show how they are related. In English, some of the most common conjunctions are 'and', 'but', and 'or', which are known as coordinating conjunctions. They are used to connect grammatically equivalent elements; 'and' is used to add or continue, 'but' is used to contrast, and 'or' is used to present alternatives or choices.