Refers to the memory system that involves holding information from the world in its original form for only an instant, not much longer than the brief time it is exposed to the visual, auditory, and other senses.

   Sensory memory

Explanation:  Sensory memory is part of the total memory and refers to that part of memory that collects and stores sensory information that is collected through sensory receptors. After this collected short-term information is collected through sensory receptors and processed in the nervous system is stored in this sensory memory. This type of memory is, in fact,  the shortest memory, since it lasts as long as the external stimulus lasted on our senses. Then, after this short-term external stimulus information, that is, sensory information, this information is transferred to short-term memory.

  b.

there are isolated pockets of farming, generally around rivers and oases, which are used for irrigation.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.