Explanation:

- Option 1: These are limited as compared to wants

- Resources such as labor, land, and capital are finite. Human desires often outpace available resources, creating scarcity.

- Option 2: These have alternative uses

- Resources can be utilized in different ways. For example, land could be used for farming or building, depending on need.

- Option 3: Both (a) and (b)

- Both statements are correct. Resources are limited and possess alternative applications.

- Option 4: None of the above

- Incorrect, as both scarcity and alternative uses accurately describe resources.

The salient features of factors/resources are indeed their limited nature and versatility in use. They underline the economic problem of scarcity and choice.

The correct option is:

Option 3: Both (a) and (b)