Which of the following words is closest in meaning to “Proprietary”?

Proprietary means owned by a private person or company.

• Correct answer - privately owned: it has the same meaning as Proprietary.
• respectable: held in good regard - wrong, it does not mean the same as Proprietary.
• aggressive: ready to attack - wrong, it does not mean the same as Proprietary.
• self-centred: concerned only with oneself - wrong, it does not mean the same as Proprietary.