Explanation:
Firstly, we need to under stand what is bound morphemes. A word is bound morpheme which cannot stand alone as a word.
Answer (a):
fearlessly----> Bound morphemes------> -less, -ly
misleads----> Bound morphemes------> mis-, -s
previewer----> Bound morphemes------> pre-, -er
shortened----> Bound morphemes------> -ed
unhappier----> Bound morphemes------> un-
Secondly, we need to under stand what is bound stem. A stem which cannot occur as separate/ apart from other morpheme.
Answer (b): All options have bound stem
construct----> Bound stem------> -struct
deceive----> Bound stem------> -ceive
introduce----> Bound stem------> -duce
repeat----> Bound stem------> -peat
Thirdly, we need to under stand what is allomorph. It is a alternative form of morpheme.
Answer (c): None of them
are -----> were
have ------> had
sitting -----> sat
wait -----> waited