The heart,lungs and brain begin to form during the embryonic period of prenatal development.
The sperm carries one chromosome of the homologous pair and the egg has also one otherchromosome homologous to the first. After fertilization, when the zygote is formed it has one chromosome from the sperm and one chromosome from the egg that was fertilized by the sperm.
The best answer should be B.
Apparatus in laboratories can be really dangerous, especially the ones which involves electricity.
As a student, he should not just wrap the cord with electric tape, as he might wrap them in a wrong way and possible could hurt himself. So A is not a good answer.
And for C, even though it is a great idea not to use the frayed cord hot plate, but he should also notify the teacher as that hot plate with frayed cord may be passed on and be used for the other students which may pose a risk to them.
And obviously, using the hot plate with frayed cord is super dangerous and he could possibly get electric shock. So D is the incorrect answer.
And it's only left to B, it right to notify the teacher so the teacher can actually either fix it themselves or they wouldn't pass on to other students to use it.
