The correct option is D All of the above
The hybridisation experiments were conducted by Mendel on around 29,000 pea plants. He chose pea plants because they had the following easily observable traits:
1. Easy to cultivate
2. Very low maintenance costs
3. Bisexual flowers
4. Self-pollinating, making self- and cross-pollination easy
5. Shorter lifespan
6. Easy to maintain