Identify the correct statement from the given options.

The splint bone of the present-day horse is a vestige of which digit?

Parallelism is defined as:

What type of evolution is shown in the figure?

Given below are four statements $(A-D)$ each with one or two blanks. Select the option which correctly fills up the blanks in two statements.
Statements:
$(A)$ Wings of butterfly and birds look alike and are the results of $ . . . . . . (i) . . . . . . $ evolution.
$(B)$ Miller showed that $CH_4, H_2, NH_3$ and $ . . . . . . (i) . . . . . . $ when exposed to electric discharge in a flask resulted in formation of $ . . . . . . (ii) . . . . . . $.
$(C)$ Vermiform appendix is a $ . . . . . . (i) . . . . . . $ organ and an $ . . . . . . (ii) . . . . . . $ evidence of evolution.
$(D)$ According to Darwin,evolution took place due to $ . . . . . . (i) . . . . . . $ and $ . . . . . . (ii) . . . . . . $ of the fittest.

About $200$ million years ago,some land reptiles went back into water to evolve into fish-like reptiles. These reptiles were known as: