Given the following lines of code in Scala:

class Date$($y: Int, m: Int, d: Int$)$ extends Ord $\{$

def year $=$ y def month $=$ m def day $=$ d

override def toString$()$: String $=$ year $+"-"+$ month $+"-"+$ day

$\}$

Choose one:

A$.$ the definition of class Date is incomplete

B$.$ Date inherits from Ord

C$.$ Ord inherits from Date

D$.$ None of these