In plants, continued self pollination results in

Inbreeding depression

The correct answer is Option (2) → Inbreeding depression

Majority of flowering plants produce hermaphrodite flowers and pollen grains are likely to come in contact with the stigma of the same flower. Continued self-pollination result in inbreeding depression. Flowering plants have developed many devices to discourage self- pollination and to encourage cross-pollination.

Outcrossing refers to the introduction of genetic material from different plants, which is the opposite of self-pollination.

Male sterility refers to the inability of plants to produce functional pollen, which is not caused by continued self-pollination.

Self-incompatibility. This is a genetic mechanism and prevents self-pollen (from the same flower or other flowers of the same plant) from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil.