How many times the larva of silk worm moult?

The larva is the silkworm caterpillar. Since the silkworm grows so much, it must shed its skin four times while it is growing. These stages-within-a-stage are called instars.

Explanation:

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.