Which of the following is the Fischer projection of $L$-threonine (also known as $(2S, 3R)-2$-amino-$3$-hydroxybutanoic acid)?

The first viral disease detected in human being was

The artificial sweetener $X$ contains a glycosidic linkage and $Y$ contains amide and ester linkages. $X$ and $Y$ respectively are:

Identify the correct statements from the following:
$I)$ When $DNA$ is hydrolysed,adenine and thymine are obtained in equal quantities.
$II)$ When $RNA$ is hydrolysed,adenine and uracil are obtained in equal quantities.
$III)$ Amylose is a branched polymer with $\alpha-1 \rightarrow 4$ and $\alpha-1 \rightarrow 6$ glycosidic linkages.
$IV)$ Addison disease is due to the abnormal functioning of adrenal cortex.

Pick out the wrong combination.

Which of the following matches is wrong?