This is a difficult question as there very little to choose from two sequences 1423 and 1432. Both the sequences are plausible, though 1 and 4 will come before 2 and 3. 'the canopy' in statement 4 refers to the woodland's canopy in statement 1.Thus 1 and 4 form a pair. The hunting process of the swifts is described in statement 3. and this hunting is not just confined to woodlands is what statement 2 says. Thus 3 and 2 form a pair. The right sequence is 1432 .