Final answer:
The correct word to fill in the blank is 'on,' making the complete sentence 'We should rely on our own efforts.' The preposition 'on' is correctly used to convey dependency in this context.
Step-by-step explanation:
Prepositions are words that show the relationship between nouns or pronouns and other words in a sentence. The sentence in question implies dependency or trust in one's own efforts. When discussing reliance, trust, or dependency in this context, the preposition on is most commonly used in English. It is correct to say that one relies on someone or something, which means to depend on them for support, help, or maintenance.
One cannot 'rely by', 'rely to', or 'rely of' something, as none of these prepositions are grammatically correct in this context. Other examples of correctly using the word 'rely' include sentences like "You can rely on me" or "They rely on their skills to succeed." Understanding the proper usage of prepositions is crucial in constructing grammatically correct sentences and conveying the intended meaning clearly.