Conversation 3.b states: 'Jogging in the morning is good! ... (Jogging is subject of the sentence in 3.b.)'. This clearly identifies 'Jogging' as the subject.
Class 6 › English Grammar and Composition › Chapter 5: The -ing form of Verb: Gerund & Participle › Topic: The -ing form of verbs: Gerund
Aligned to the NCTB national curriculum.