No single cap will depart from perpendicularity to the axis more than how many degrees according to C617?

The correct answer is based on the guidelines established in ASTM C617, which pertains to the practice of using maturity meters and testing for the measurement of concrete specimens within testing molds. The standard specifies tolerances for how caps must be applied to specimens to ensure that they are perpendicular to the axis of the specimen.

According to ASTM C617, a cap should not deviate more than 0.5 degrees from being perpendicular to the axis of the test specimen. This degree of precision is necessary to ensure accurate and reliable measurements of strength and other properties of the concrete. Allowing a deviation greater than this could introduce significant errors in test results, leading to incorrect assessments of the material's performance characteristics.

The other options present either larger angles or inappropriate tolerances that do not conform to the specified limits set out in the standard, which is why they are not the correct answer. Maintaining strict compliance with the guidelines ensures the integrity of testing procedures and results in the field of concrete testing.