What is the best replacement for the underlined word in the following sentence? the monkeys' attention and choices were random when more than four objects were shown. a. all over the place c. few b. inaccurate d. selective

Since you said in the comment above that the underlined word is "random", I'd also say that the best replacement for it would be "inaccurate".

Explanation:

When we take some of the synonyms of random into consideration, we can conclude the the best replacement for it is the word "inaccurate":

- purposeless;

- unaimed;

- unplanned;

- incidental etc.

Inaccurate presents, among its synonyms, the following:

- careless;

- imprecise.

Something that has no purpose, that is not planned, is the same as something that has no care, no precision. Thus, we could replace random for inaccurate.