Acontraceptive that permanently prevents transport of the sperm or egg to the site of conception is a

The answer is Surgical Contraceptive Methods e.g. Vasectomy(For males) and  Tubectomy(Females).

Vasectomy:- In this method vas deference is cutted and tied so that sperms can't reach uthera.

Tubectomy:- In this method both fallopian tubes are cut and tied, so that no egg can head towards the site of reproduction(Cervix).

Note:- Both process are irreversible.

Compound light microscope

B.) nitrogen fixationnitrogen fixation is the process of nitrogen molecules seeping into the soil and inside plant roots and bacteria. it gives more "life" to plants