Which of the following provides the most durable wood?

$Acacia arabica$ is a

Where will you get spiny stipules for protection against grazing animals?

How many series does the sub-class Gamopetalae contain?

$A$. Citrus and Ricinus have synandrous condition.
$B$. In epitepalous condition,the cohesion occurs between tepal and filament of stamen.
$C$. Tetradynamous condition consists of two long and four short stamen filaments.

Match the plants in Column-$I$ with their specific floral characteristics in Column-$II$ and select the correct option.

Column-$I$	Column-$II$
$(A)$ China rose	$(p)$ Thalamus disc-shaped
$(B)$ Lemon	$(q)$ Ovary inferior
$(C)$ Rose	$(r)$ Thalamus dome-shaped
$(D)$ Sunflower	$(s)$ Perianth
$(E)$ Bougainvillea	$(t)$ Thalamus cup-shaped
	$(u)$ Ovary superior