Digraphs are voiced combinations of two or three consonants. t f 

This sentence is false.
Digraphs are indeed combinations of letters, however, they are combinations of only two letters (di- means two in Greek). Additionally, these combinations don't have to be only consonants, but rather vowels as well. Combinations of two or three consonants are called blends, not digraphs. 

The answer is 2) to show the depth of the colonists’ commitment to independence