Class – Aves : 1. Heart is completely four- chambered. 2. Respiration is by lungs. 3. Air sacs connected to lungs supplement respiration. Regarding 1,2 and 3:

Question

( a ) All are correct
( b ) 2 is incorrect but 1 and 3 are correct
( c ) 1 is incorrect but 2 and 3 are correct
( d ) 3 is incorrect; 1 and 2 are correct