What should be used for the maintenance of personal health?

$DPT$ vaccine doses are administered at specific intervals after birth. Identify the correct sequence for the $1^{st}$, $2^{nd}$, and $3^{rd}$ doses of $DPT$ from the following list:
$I$. $6 \; \text{weeks}$ after birth
$II$. $10 \; \text{weeks}$ after birth
$III$. $14 \; \text{weeks}$ after birth
$IV$. $24 \; \text{weeks}$ after birth
$V$. $29 \; \text{weeks}$ after birth

The drug used for diarrhea and piles is ...... .

What is the primary function of analgesic drugs?

The discovery of antibiotics is considered a significant achievement of which century?

Certain pathogens are tissue/organ specific. Justify the statement with suitable examples.