Question

read the passage and then answer the question.
at high latitudes, one might look into the night sky and see dazzling curtains of colorful light. this brilliant sight, known as an aurora, is the result of solar winds. solar winds occur when the outer layers of the sun boil off due to the intense heat, emitting streams of magnetically charged particles into the surrounding space.
some of these solar wind particles end up traveling in earth’s direction. if unimpeded, these particles would have deleterious effects on human health, increasing the risk of heart failure and other health problems. but earth’s magnetic poles—located near the geographic north and south poles—create a magnetic field that protects the planet from end up colliding with oxygen and nitrogen in earth’s atmosphere. the collisions release energy, thus creating the aurora’s stunning display.
what is the meaning of deleterious as used in the passage?
contagious
harmful
unpredictable
unnoticeable

Explanation:

The passage states that unimpeded solar wind particles would have "deleterious effects" including increased risk of heart failure and other health problems. This context shows the word refers to something causing harm.

Answer:

harmful