Cross-pollination is favoured by

• (a) Self-sterility
• (b) Dichogamy
• (c) Herkogamy and heterostyly
• (d) All of these

Cross-pollination is a process where pollen from one flower fertilizes the ovule of another flower. Several mechanisms promote this process, including:

Factors Promoting Cross-Pollination

• Self-sterility: This condition prevents a flower from fertilizing itself, encouraging pollen transfer from other plants.
• Dichogamy: This refers to the timing of pollen release and stigma receptivity being staggered, which reduces self-fertilization.
• Herkogamy and Heterostyly: These traits involve structural differences that prevent self-pollination, promoting genetic diversity through cross-pollination.

Given these factors, the correct answer is (d) All of these, as each mechanism supports cross-pollination in different ways.