Related Rule
Côte d’Ivoire
Practice Relating to Rule 21. Target Selection
Côte d’Ivoire’s Teaching Manual (2007) provides in Book IV (Instruction of heads of division and company commanders):
When a choice is possible between several legitimate military objectives for obtaining a similar military advantage, the objective to be selected shall be that the attack on which may be expected to cause the least danger to civilian lives and to civilian objects. 
Côte d’Ivoire, Droit de la guerre, Manuel d’instruction, Livre IV: Instruction du chef de section et du commandant de compagnie, Manuel de l’élève, Ministère de la Défense, Forces Armées Nationales, November 2007, p. 28.