Question
Consider the following pairs:
Objects in space | Description
1. Cepheids | Giant clouds of dust and gas in space
2. Nebulae | Stars which brighten and dim periodically
3. Pulsars | Neutron stars that are formed when massive stars run out of fuel and collapse
How many of the above pairs are correctly matched?
Explanation
Pair 1 is incorrect: Cepheids are actually stars that brighten and dim periodically — that description has been swapped with Nebulae’s definition here.
Pair 2 is incorrect: A Nebula is genuinely a giant cloud of dust and gas, the birthplace (or remnant) of stars — the exact opposite pairing to what’s listed.
Pair 3 is correct: Pulsars truly are rapidly-rotating neutron stars, formed when a massive star runs out of fuel, collapses, and explodes as a supernova, leaving behind a dense spinning core.
With only pair 3 correct, the answer is Option A.