Birds and mammals have

Which of the following is common among a leech,a mosquito,a bed bug,and a rat?

Which of the following options represents hermaphrodite (bisexual) animals?

Which one of the following groups of three animals is correctly matched with their one characteristic morphological feature?

Fill in the blanks marked in the classification table of $Vertebrata$ from the choices provided below with respect to $A, B, C, D, E$ and $F$ and choose the correct option:
$I$. Pisces
$II$. Osteichthyes
$III$. Agnatha
$IV$. Gnathostomata
$V$. Chondrichthyes
$VI$. Cyclostomata
$A - B - C - D - E - F$

Match the name of the animal with one characteristic and the phylum/class to which it belongs.