Arguments to Explain Why Most Equity Issues Are Underwritten Versus

Arguments to explain why most equity issues are underwritten versus sold through a rights offering are:

A) underwriters buy at an agreed upon price and bear some risk of selling the issue.
B) cash proceeds are available sooner in underwriting and the issue is available to a wider market.
C) investment bankers can provide market advice and certify the issue for potential investors.
D) All of these.
E) None of these.