Multiple choice Babies who use a walker skip some of this magnificent _________ journey. developmental develop development breakthrough Reveal answer Fill a bubble to check yourself A Correct answer Explanation We need an adjective to modify the noun 'journey'. 'Developmental' is the correct adjective form. 'Develop' is a verb, 'development' is a noun, and 'breakthrough' does not grammatically or contextually fit as well as 'developmental'.