2nd one is the right answer
Mendel's was sucessful geneticist becasue of the following reasons
1) he worked on pisum sativum which is bisexual
2) short duration of life cylce
3) its an annual plant
4) he was also having gud knowleged of statics
Its found in the body's tissues.
Hope that helps. I can give a more detailed answer if you need one. <span />