Given below are two premises (a and b). From those two premises four conclusions (i), (ii), (iii) and (iv) are drawn. Select the code that states the conclusion/conclusions drawn validly (taking the premises singularly or jointly). 
Premises: 
a) All bats are mammals. 
b) No birds are bats. 
Conclusions: 
i. No birds are mammals. 
ii. Some birds are not mammals. 
iii. No bats are birds. 
iv. All mammals are bats.