Question

in 1986, the worlds worst nuclear power plant accident occurred at chernobyl, ukraine, in the former soviet union. a chemical explosion and fire released more than fifty tons of radiation into the atmosphere. an emergency team responded by pouring boron and sand on the debris. the boron was meant to prevent more nuclear reactions; the sand was to stop the fire and release of radiation. soon after the accident, a team built a concrete and steel structure, known as a sarcophagus, to prevent rainwater from causing another explosion. over time, however, a new complication arose: the structure eroded. this crisis inspired more than forty countries and organizations to find a better answer. an enormous structure called the new safe confinement (nsc) was built. the nsc covers the sarcophagus and forms an airtight seal.
match the problems with their solutions.
rainwater might have triggered another explosion.
erosion damaged the sarcophagus.
the explosion caused a fire.
problem
solution
a crew poured sand on the reactor.
a crew built a concrete structure to seal the reactor.
the nsc was built.

Explanation:

Step1: Find solution for "Rainwater might have triggered another explosion."

The text says "a team built a concrete and steel structure, known as a sarcophagus, to prevent rainwater from causing another explosion." So the solution is "A crew built a concrete structure to seal the reactor."

Step2: Find solution for "Erosion damaged the sarcophagus."

The text says "a new complication arose: the structure eroded. This crisis inspired...the New Safe Confinement (NSC) was built." So the solution is "The NSC was built."

Step3: Find solution for "The explosion caused a fire."

The text says "An emergency team responded by pouring boron and sand on the debris...the sand was to stop the fire". So the solution is "A crew poured sand on the reactor."

Answer:

Rainwater might have triggered another explosion - A crew built a concrete structure to seal the reactor.
Erosion damaged the sarcophagus - The NSC was built.
The explosion caused a fire - A crew poured sand on the reactor.