The correct option is
D got
The given sentence is a Type 2 (second) conditional, because it presents a hypothetical condition (if-clause) and its probable result.
In
such sentences, the if-clause is in simple present tense and the main
clause is a present conditional "would feel better".
Option A: 'Got' is in the simple past
tense. It completes the sentence in meaning as well as agrees with the
Type 2 structure. Hence option A is correct.
Option B: 'Gets' is in the simple present tense. It isn't used in the second conditional.
Options
C and D: Similarly, 'will get' refers to the future tense, and 'has gotten' refers to the present perfect tense.
They aren't used in the second conditional.
Hence options B, C and D are incorrect.