Extraneous marks that interfere with EKG tracing interpretation are called...

Glitches refer to unexpected errors or malfunctions in electronic systems, but in the context of EKGs, this term does not specifically describe the extraneous marks. While glitches may affect electronic devices, they are not a recognized term for the artifacts that can appear on EKG tracings.

Smears may imply a blurring or spreading of the tracing, but they do not encompass the broader range of extraneous marks that can disrupt EKG readings. This term is not commonly used in medical terminology to describe the types of interferences encountered in EKG interpretation.

Lines could refer to various straight or irregular markings that might appear on an EKG, but this term is too vague and does not accurately capture the concept of artifacts. Artifacts may manifest as lines, but the term itself lacks specificity and recognition in the context of EKG tracing interpretation.