Final answer:
A reliable test will most likely have a strong positive correlation among its items and a larger number of items to ensure consistency and generalizability of the test results, making option (c) the correct answer.
Step-by-step explanation:
The question is asking for the characteristics of a reliable test in terms of the correlation between test items and the direction and size of that correlation. A positive correlation means that the test items move in the same direction; as one item score increases, so does the other. This is indicative of internal consistency and therefore, reliability. On the other hand, a negative correlation would mean that the items move in opposite directions, which can indicate an unreliable test. Also, the more items (large number of items) a test has, the more reliable it generally is, assuming those items are measuring the same construct.
Considering these points, the reliable test can have a positive correlation and a large number of items, which makes option (c) the correct answer. The number of items helps with the reliability by adding more data points, which leads to a more consistent and generalizable result. A high correlation coefficient (close to 1), reflects a strong relationship, irrespective of whether it is positive or negative, but for a test, we desire a positive correlation amongst its items.