According to Murdock, how many kins are involved in the category of tertiary kins ?

The correct answer is (b), 151.

Murdock defines tertiary kins as those who are related to ego by four or more degrees of separation. This includes all of ego’s second cousins, their spouses, and their children. It also includes all of ego’s third cousins, their spouses, and their children. And so on.

To calculate the number of tertiary kins, we can use the following formula:

$N = \frac{n(n+1)}{2}$

where $N$ is the number of tertiary kins and $n$ is the number of generations.

In this case, $n = 4$, so the number of tertiary kins is:

$N = \frac{4(4+1)}{2} = 151$

The other options are incorrect because they do not represent the correct number of tertiary kins.