Question

A sample of households in a community is selected at random from the telephone directory. in this community, 4% of households have no telephone and another 35% have unlisted telephone numbers. the sample will certainly suffer from

Answer 1

The sample certainly suffer from undercoverage bias .

When some members of population aren't represented in sample , it's called undercoverage bias . In simple way you can say that when some members of population have no any chance to select in survey or experiment.
Example : people who don't like the mall, people who want to be great business man .

Answer 2

Solution :-

The sample will certainly suffer from undercoverage bias.

Undercoverage is type of selection bias. Undercoverage occurs when an element of a population is not represented on the survey frame and therefore not given any chance of selection in the survey sample, that is, the element has zero probability of selection into the sample. Undercoverage is the most serious type of coverage error because it can be difficult to detect and even more difficult to solve. Therefore, preventing undercoverage  is often a priority during survey design.