Which of the following happens during the first trimester?

The answer is The fundamentals of real organ frameworks show up.  

Explanation:

First trimester: key stages. The principal trimester starts on the main day of your last period and keeps going until the finish of week 12. This implies when you know for beyond any doubt you're pregnant, you may as of now be five or a month and a half pregnant! A great deal occurs amid these initial three months. First trimester: key stages. The principal trimester starts on the main day of your last period and keeps going until the finish of week 12. This implies when you know for beyond any doubt you're pregnant, you may as of now be five or a month and a half pregnant! A considerable measure occurs amid these initial three months.