Each question consist of two words which have a certain relationship to each other followed by four pairs of related words. Select the pair which has the same relationship. TEN : DECIMAL

The term "DECIMAL" refers to a number system that uses base TEN. So, "TEN" is the base of the "DECIMAL" system.

• a. four : quartet A quartet is a group of four. This describes a quantity and a group of that quantity, not a base system.
• b. seven : septet A septet is a group of seven. Similar to a quartet, this describes a quantity and a group of that quantity, not a base system.
• c. two : binary The term "BINARY" refers to a number system that uses base TWO. This perfectly matches the relationship where the first word is the base of the system described by the second word.
• d. five : quince A quince is a type of fruit. This pair does not have a numerical or base-system relationship.

The relationship "TEN : DECIMAL" signifies that "TEN" is the base of the "DECIMAL" number system. The pair "two : binary" exhibits the same relationship, where "two" is the base of the "binary" number system.

The correct option is c.

The final answer is $\boxed{\text{c. two : binary}}$