Explanation:

- As of October 2019, the ICC World Test Championship was a newly introduced format aimed at providing a league format for Test cricket, thus adding context to all Test series among the top cricketing nations.

- Option 1: South Africa

- South Africa had faced challenges in performance during various Test matches in that period.

- Option 2: Australia

- Australia had shown good performances but were not at the top of the table by October 2019.

- Option 3: India

- India was leading the ICC World Test Championship table at that time, thanks to their dominant performances in bilateral series.

- Option 4: England

- England was competitive but not at the top in the Championship table during the period in question.