The difference between a dealer's bid and ask price is the

$-$

$.$ Select all that apply

Which statements are true about Rule $415$ and its consequences?

Multiple select question.

Registered securities are said to be $"$on the shelf."

It allows securities to be sold on short notice, with little additional paperwork.

Securities can be sold in small amounts, but will have substantial flotation costs.

It was introduced in $1982.$