Tropical regions show the greatest level of species richness because:
$A$. Tropical latitudes have remained relatively undisturbed for millions of years,hence more time was available for species diversification.
$B$. Tropical environments are more seasonal.
$C$. More solar energy is available in the tropics.
$D$. Constant environments promote niche specialization.
$E$. Tropical environments are constant and predictable.
Choose the correct answer from the options given below.

• A
  $A$ and $B$ only
• B
  $A, B$ and $E$ only
• C
  $A, B$ and $D$ only
• D
  $A, C, D$ and $E$ only