Which sentence uses the conditional form of the verb send?

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2 points
I could send a letter to our grandparents.
I am sending a letter to our grandparents.
I suggest you send a letter to our grandparents.
Send a letter to our grandparents.

I could send a letter to our grandparents.

The sentence that uses the conditional form of the verb "send" is: "I could send a letter to our grandparents."