Respuesta :
Answer:
Third trimester—major organs completely form; neurulation occurs
and
Second trimester—bone starts to replace cartilage; fetus begins to produce urine
Answer:
The answer is "Second trimester--bones start to replace cartilage; fetus begins to produce urine"
Explanation:
Around week 13 is when the 2nd trimester starts, which is also when urine is produced and bones replace cartilage! I took human biology and learned this too! :)