I'm stuck on this multiple choice problem about a base substitution mutation that increases the stability of a protein (see image), can someone explain the answer?

Tamarind can be grown on homesteads, plantations, and wasteland or as a forest tree. methods of propagating tamarind there are two methods of propagating tamarind trees: seed propagation and vegetative propagation. seed propagation: it involves the collection, preparation and direct planting of the seed.answer from google full credit to google.