问题如下：
Which of the following regarding collateral backing is most likely incorrect?
选项：
A.Covered bonds are debts backed by financial assets.
B.Mortgage-backed security is a type of ABS backed by mortgages.
C.Equipment trust certificates are backed by physical assets.
解释：
A is correct.
Covered bonds are backed by a segregated pool of assets which is called a 'covered pool'. Securities that are backed by financial assets are called collateral trust bonds.
什么是backed by financial assets? 什么是callable trust bond?
