Read the sentence from "excerpt from President Richard Nixon’s News Conference: The President’s Personal Finances." They said, you know, "How is it that President Nixon could have a very heavy investment in a fine piece of property in San Clemente and a big investment in a piece of property in Florida," in which I have two houses, one which I primarily use as an office and the other as a residence, and also an investment in what was my mother's home, not very much of a place but I do own it—those three pieces of property."

Knowing that primarily and hardly are antonyms, what is the definition of primarily?

cautiously

incorrectly

secondarily

mainly