Meaning: 'Programmed' means set up or configured to perform a specific task.

Wrong options:

• calculate: 'Calculate' is a verb that does not fit grammatically as it does not describe the state of the GPS receivers; instead, it describes an action they perform.
• prioritized: 'Prioritized' is a past participle that implies a ranking or importance, which does not apply to the function of GPS receivers in this context.
• constrained: 'Constrained' suggests being limited or restricted, which does not accurately describe how GPS receivers operate in relation to receiving information.
• constant: 'Constant' is an adjective that describes something unchanging, but it does not fit the grammatical structure needed for this blank, which requires a verb form.
• testify: 'Testify' is a verb that means to declare or affirm, which does not relate to the function of GPS receivers and does not fit grammatically.

Correct answer: constant

Explanation: The term 'constant' is an adjective that describes the speed of radio waves as being unchanging. This fits grammatically as it modifies the noun 'speed' and provides essential information about the nature of the speed relevant to the context of GPS technology.

Meaning: 'Constant' means unchanging or steady over time.

Wrong options:

• calculate: 'Calculate' is a verb that does not fit as it does not describe the speed; it refers to an action rather than a characteristic of speed.
• programmed: 'Programmed' is a past participle that describes the receivers, not the speed, and thus does not fit in this context.
• prioritized: 'Prioritized' is an adjective that implies a ranking, which does not apply to the speed of radio waves.
• constrained: 'Constrained' suggests limitations, which does not accurately describe the nature of speed in this context.
• testify: 'Testify' is a verb that means to declare or affirm, which does not relate to the description of speed.

Correct answer: calculate

Explanation: The word 'calculate' is a verb that indicates the action the GPS receiver performs to determine its distance from satellites. This fits grammatically as it follows the structure of the sentence, which describes what the receiver does with the time measurements.

Meaning: 'Calculate' means to determine mathematically or to figure out.

Wrong options:

• constant: 'Constant' is an adjective that does not fit grammatically as it does not describe an action; it describes the nature of speed.
• programmed: 'Programmed' is a past participle that describes the state of the receivers, not an action they perform, and thus does not fit here.
• prioritized: 'Prioritized' is a past participle that implies ranking, which does not relate to the action of determining distance.
• constrained: 'Constrained' suggests limitations, which does not apply to the action of calculating distance.
• testify: 'Testify' is a verb that means to declare or affirm, which does not relate to the action of calculating distance.