In which of the following sections of the Bharatiya Nyaya Sanhita, 2023 is ‘preparation’ punishable?

Preparation is generally not punishable, but the Bharatiya Nyaya Sanhita, 2023 punishes it in a few cases: section 149 (collecting men, arms or ammunition or otherwise preparing to wage war against the Government of India), section 154 (committing, or making preparations to commit, depredation on the territories of a foreign State at peace with the Government of India) and section 310(4) (making preparation to commit dacoity), formerly sections 122, 126 and 399 IPC. So the answer is "Sections 149, 154, 310(4)". Section 147 punishes waging war itself, section 153 waging war against the Government of a foreign State at peace with the Government of India, and section 312 attempting robbery or dacoity when armed with a deadly weapon.