When released into the atmosphere, refrigerant A damages the earth’s ozone layer. A new kind of refrigerant B does not have this effect. The manufacturer claims that replacing A with B in both new and existing refrigerators will prevent any further damage done by A to the ozone layer apart from the damage done by A already in the atmosphere;
Which of the following must be true if the manufacturer’s claim is to prove accurate ?

According to one psychological theory, in order to be happy, one must have an intimate relationship with another person. Because the world’s greatest composers spent most of their time in solitude and had no intimate relationships, the psychological theory must be wrong.
What is the assumption underlying the above conclusion ?

Chitra is shorter than Jehan, but taller than Epa. Chandra is shorter than Epa. William is taller than Chandra, but shorter than Jehan.
If the above statements are true, which of the following must also be true for one to validly conclude that “Berty is shorter than Chitra”?