What is a milestone for language development in one- to two-year-olds?
a. putting two words together
b. having words for almost everything around them
c. following directions and doing two things at once
d. understanding most of what is said by those closest to them

Language Milestones: 1 to 2 Years. Language milestones are successes that mark various stages of language development. They are both receptive (hearing and understanding) and expressive (speech). This means that in addition to being able to make sounds and words, your baby also needs to be able to hear and understand.

so D

Explanation:

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.