In which trimester does the following occur? the respiratory system becomes mature.

third trimester

During the third trimester, the airspaces of most peripheral airways are mostly widened and lengthened, fibroblastic cells produce extracellular matrix, collagen and elastin and the vascular tree increases in diameter and length. These developments support epithelial differentiation and surfactant secretion. At week 32, the baby practices his breathing.

hmmm

true, i think.

i checked and it seems the answer is, true.

i don't think so because different teachers have different materials. tehy teach differently, unless you know for sure your teacher is the exact same as others. i would just contact ur teacher