Question

it is important to learn about health issues at ____ past stages of life your pet’s stages of life other people’s stages of lives each life stage

Explanation:

Learning about health - issues is important throughout one's life, at each life - stage. Past stages are in the past and not relevant for current learning. Pet's and other people's life - stages are not as directly relevant as one's own life - stages for personal health knowledge.

Answer:

D. each life stage