Nicotine is an alkaloid that enters the body through smoking. How many of the following characteristics are associated with its effects?
$(i)$ Increases blood pressure
(ii) Decreases respiratory rate
(iii) Causes cancer of the lungs,throat,and bladder
(iv) Induces allergies
$(v)$ Can cause emphysema
(vi) Decreases the level of $O_2$ in the blood

• A
  $4$
• B
  $6$
• C
  $3$
• D
  $2$