Final answer:
M&M's business was affected by increased competition in the domestic market due to a German company entering and offering similar products at lower prices.
Step-by-step explanation:
The element in the marketing environment that has affected M&M's business in the scenario described is Competition in the domestic market. The entrance of a German company selling similar high-quality products at lower prices has intensified the competition for M&M within its own market. This represents a shift in the market structure influenced by globalization, where firms now contend not just with local competitors but also with those coming from international markets.