In a plant showing sporophytic incompatibility which one of the following crosses is successful in producing a zygote?

• A. S1 pollen from S1S1 flowers and the ovule of S1S1 flowers
• B. S1 pollen from S1S1 flowers and the ovule of S2S3 flowers
• C. S2 pollen from S2S3 flowers and the ovule of S2S3 flowers
• D. S3 pollen from S1S3 flowers and the ovule of S3S3 flowers

Answer: (B)