When past memories are lost either for minutes or several years, the individual probably has amnesia.?

The answer is

Retrograde Amnesia

Explanation

Retrograde amnesia is usually caused by head injury, cerebrovascular accident, stroke, tumor, encephalitis, chronic alcoholism or brain damage to parts of the brain besides the hippo campus. People suffering from retrograde amnesia are more likely to remember general knowledge rather than specifics.

Retrograde amnesia is usually temporary and can be easily recovered by exposing the  patient to memories from the past.

which ever one is showing doing the same exercise in time intervals such as 30 seconds or a minute several times.

c. flammable gases, patient lying in standing water, combustible liquids near the victim