Refer to the following statements for agarose-gel electrophoresis:
$(a)$ The $\text{DNA}$ fragments resolve according to their size.
$(b)$ The separated $\text{DNA}$ fragment can be visualised only after staining with ethidium bromide followed by exposure to $UV$ radiation.
$(c)$ $\text{DNA}$ is always loaded into the well.
$(d)$ The smallest fragment of $\text{DNA}$ is near the well.
Choose the correct statements:

• A
  $(a)$ and $(b)$ only
• B
  $(a), (b)$ and $(c)$ only
• C
  $(a), (b)$ and $(d)$ only
• D
  $(b), (c)$ and $(d)$ only