This question concerns self-incompatibility (SI) systems in cauliflower.
Statement (I): Heat tolerant tropical cauliflowers show significantly high level of self-incompatibility.
This statement is true. Many Indian or tropical cauliflower types, which are adapted to warmer conditions, exhibit strong sporophytic self-incompatibility. This SI system promotes outcrossing and is an important consideration in their breeding and seed production.
Statement (II): The European annual or snowball types are basically self-compatible in nature.
This statement is also true. Unlike the tropical types, many European annual cauliflower varieties, often referred to as "snowball" types (e.g., Snowball A, Snowball Y), have been selected for self-compatibility. This means they can set seed effectively through self-pollination, which simplifies pure line seed production for these varieties.
Since both statements accurately describe the compatibility systems in these distinct groups of cauliflower, option (1) is correct.
Both Statement (I) and Statement (II) are true.