What is the fate of pyruvic acid under anaerobic conditions in our body?

Given below are two statements.
$Statement-I$ - Skeletal muscles usually derive energy by anaerobic respiration.
$Statement-II$ - After vigorous exercise,lactic acid accumulates in muscle fibres,leading to muscle fatigue.
In the light of the above statements,choose the most appropriate answer from the options given below:

Fermentation is a/an ...... process.

Identify the enzyme for the following reaction:
$CH_3COCOOH \longrightarrow CH_3CHO + CO_2$

In which one of the following processes $CO_2$ is not released?

In anaerobic respiration,the pyruvic acid in muscle will form: