Multiple Choice, Single Answer

Read the passage and answer the question.

Lightning seems to strike at random, but it follows a clear physical logic. Inside a storm cloud, colliding ice particles and water droplets strip electrons from one another, leaving the upper cloud positively charged and the base strongly negative. This separation builds an enormous voltage between the cloud and the ground. When the gap finally breaks down, a faint channel of charged air reaches downward, meeting an upward spark from a tall object below. The return surge that races up this channel is the brilliant flash we see. Tall, pointed, isolated objects are favoured simply because they shorten the distance the charge must jump.