Which enzyme was the first to be discovered?

Regarding the catalytic cycle of an enzyme action,select the correct sequential steps:
$A$. Substrate-enzyme complex formation.
$B$. Free enzyme ready to bind with another substrate.
$C$. Release of products.
$D$. Chemical bonds of the substrate broken.
$E$. Substrate binding to active site.
Choose the correct answer from the options given below:

Which of the following statements is correct?

In seeds,digestion is made possible at relatively low temperatures by:

The enzyme $Lactate \text{ } Dehydrogenase$ belongs to which class of enzymes?

What does $Q$ represent in the given figure?