If the tail of a snake is flat, laterally compressed, it is sea snake and is poisonous. If the tail ends bluntly, it is non-poisonous. If the tail is round cylindrically and pointed, it may be poisonous or non-poisonous.If the tail is round and not compressed, then examine the ventrals. If the ventrals are small and narrow, it is a non-poisonous snake. In some non-poisonous snakes (like Python), the ventrals are fairly broad but do not extend completely across the belly, Thus, the correct answer is option A.