Question 3
What is the advantage of cross-pollination over self-pollination?
The right answer is the one marked above.
It allows the characteristics of two plants to be mixed. That helps produce a strong new generation carrying new characteristics — which is why so many flowers are adapted to avoid self-pollination.
“It allows pollination to happen without any agent” is backwards: cross-pollination needs an agent, and doing without one is self-pollination's advantage. Seeds without fertilisation is parthenocarpy, a different thing again.