India, June 28 -- Ayushmann Khuranna has shot Anubhav Sinha's upcoming film 'Article 15' in Lucknow and is currently shooting Amar Kaushik's 'Bala', followed by Shoojit Sircar's 'Gulabo Sitabo' in the state capital. During a chat with HT City he said 'Article 15' is his most challenging film. Excerpts:...